U.S. patent application number 11/819841 was filed with the patent office on 2008-01-24 for heat-sensitive transfer image-receiving sheet, producing method thereof and image-forming method.
This patent application is currently assigned to FUJIFILM Corporation. Invention is credited to Kiyoshi Irita.
Application Number | 20080020931 11/819841 |
Document ID | / |
Family ID | 38972142 |
Filed Date | 2008-01-24 |
United States Patent
Application |
20080020931 |
Kind Code |
A1 |
Irita; Kiyoshi |
January 24, 2008 |
Heat-sensitive transfer image-receiving sheet, producing method
thereof and image-forming method
Abstract
A heat-sensitive transfer image-receiving sheet having, on a
support, at least one receptor layer, and at least one heat
insulation layer containing hollow polymer particles which layer is
provided between the support and the receptor layer, wherein the
hollow polymer particles have an average particle diameter of 0.3
to 1.0 .mu.m; and wherein, in the hollow polymer particles, the
ratio of the number of bulky particles having a particle diameter
of 10 .mu.m or more is less than 1/5,000 of the total number of the
hollow polymer particles; a producing method thereof, and an image
forming method using the same.
Inventors: |
Irita; Kiyoshi;
(Ashigarakami-gun, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
FUJIFILM Corporation
Tokyo
JP
|
Family ID: |
38972142 |
Appl. No.: |
11/819841 |
Filed: |
June 29, 2007 |
Current U.S.
Class: |
503/227 |
Current CPC
Class: |
B41M 2205/32 20130101;
B41M 2205/36 20130101; B41M 5/44 20130101; B41M 2205/06 20130101;
B41M 2205/12 20130101; B41M 5/5254 20130101; B41M 2205/38 20130101;
B41M 5/41 20130101 |
Class at
Publication: |
503/227 |
International
Class: |
B41M 5/50 20060101
B41M005/50 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2006 |
JP |
2006-180793 |
Claims
1. A heat-sensitive transfer image-receiving sheet, comprising, on
a support, at least one receptor layer, and at least one heat
insulation layer containing hollow polymer particles which layer is
provided between the support and the receptor layer, wherein the
hollow polymer particles have an average particle diameter of 0.3
to 1.0 .mu.m; and wherein, in the hollow polymer particles, the
ratio of the number of bulky particles having a particle diameter
of 10 .mu.m or more is less than 1/5,000 for the total number of
the hollow polymer particles.
2. The heat-sensitive transfer image-receiving sheet according to
claim 1, wherein the hollow polymer particles are non-foaming type
hollow particles of a type which has a hollow formed by
vaporization of a dispersion medium inside of a capsule wall of
each particle, after application and drying of a coating solution
thereof.
3. The heat-sensitive transfer image-receiving sheet according to
claim 1, wherein the heat insulation layer further contains a
water-soluble polymer.
4. The heat-sensitive transfer image-receiving sheet according to
claim 3, wherein the water-soluble polymer is a gelatin and/or a
polyvinyl alcohol.
5. The heat-sensitive transfer image-receiving sheet according to
claim 1, wherein the receptor layer contains at least one kind of
polymer having repeating units derived from vinyl chloride.
6. The heat-sensitive transfer image-receiving sheet according to
claim 1, wherein the heat insulation layer is formed on the support
by a method of using an aqueous coating solution.
7. The heat-sensitive transfer image-receiving sheet according to
claim 1, wherein the receptor layer and the heat insulation layer
are applied by a simultaneous multilayer coating.
8. The heat-sensitive transfer image-receiving sheet according to
claim 1, wherein the support comprises a base paper and a
polyolefin resin layer that is provided on both side or at least on
the side of the base paper to which the receptor layer is
provided.
9. A method of producing a heat-sensitive transfer image-receiving
sheet, comprising the steps of: preparing hollow polymer particles
having an average particle diameter of 0.3 to 1.0 .mu.m, removing
bulky particles having a particle diameter of 10 .mu.m or more
contained in the hollow polymer particles, to a ratio of the number
of the bulky particles being less than 1/5,000 for the total number
of the hollow polymer particles, and forming a heat-sensitive
transfer image-receiving sheet that has, on a support, at least one
receptor layer, and at least one heat insulation layer provided
between the support and the receptor layer, with using the hollow
polymer particles, to form the heat insulation layer.
10. A method of forming an image, which method comprises the steps
of: superposing the heat-sensitive transfer image-receiving sheet
according to claim 1 upon a transfer material comprising a
solid-phase ink layer, and applying a thermal energy from a thermal
head of a thermal transfer printer, and forming an image on the
receptor layer of the heat-sensitive transfer image-receiving
sheet.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a heat-sensitive transfer
image-receiving sheet, a producing method thereof and an
image-forming method.
BACKGROUND OF THE INVENTION
[0002] Various heat transfer recording methods have been known so
far. Among these methods, dye diffusion transfer recording systems
attract attention as a process that can produce a color hard copy
having an image quality closest to that of silver salt photography
(see, for example, "Joho Kiroku (Hard Copy) to Sono Zairyo no
Shintenkai (Information Recording (Hard Copy) and New Development
of Recording Materials)" published by Toray Research Center Inc.,
1993, pp. 241-285; and "Printer Zairyo no Kaihatsu (Development of
Printer Materials)" published by CMC Publishing Co., Ltd., 1995, p.
180). Moreover, this system has advantages over silver salt
photography: it is a dry system, it enables direct visualization
from digital data, it makes reproduction simple, and the like.
[0003] In this dye diffusion transfer recording system, a
heat-sensitive transfer sheet (hereinafter also referred to as an
ink sheet) containing dyes is superposed on a heat-sensitive
transfer image-receiving sheet (hereinafter also referred to as an
image-receiving sheet), and then the ink sheet is heated by a
thermal head whose exothermic action is controlled by electric
signals, in order to transfer the dyes contained in the ink sheet
to the image-receiving sheet, thereby recording an image
information. Three colors: cyan, magenta, and yellow, are used for
recording a color image by overlapping one color to other, thereby
enabling transferring and recording a color image having continuous
gradation for color densities.
[0004] In such a recording method in dye diffusion transfer system,
it has been known that it is important to make the image-receiving
sheet have high heat insulation and cushion properties in order to
give a favorable image (see, for example, "Joho Kiroku (Hard Copy)
to Sono Zairyo no Shintenkai (Information Recording (Hard Copy) and
New Development of Recording Materials)" published by Toray
Research Center Inc., 1993, pp. 241-285 and "Printer Zairyo no
Kaihatsu (Development of Printer Materials)" published by CMC
Publishing Co., Ltd., 1995, p. 180).
[0005] Thus, in some cases, a composite support using a biaxially
oriented (stretched) polyolefin film containing microvoids was used
as a base material for the image-receiving sheet to make the sheet
have more heat insulation and cushion properties (see, for example,
U.S. Pat. No. 866,282 and JP-A-3-268998 ("JP-A" means unexamined
published Japanese patent application)). However in this method,
there was occasionally caused a problem that the image-receiving
sheet was wrinkled or curled by shrinkage due to relaxation of the
residual stress after stretching by the heat during printing or the
heat during formation of the image-receiving layer.
[0006] As other known methods of making the image-receiving sheet
show heat insulation and cushion properties, a method in which, for
example, a foaming layer composed of a resin and a foaming agent
(see, e.g., Japanese Patent No. 2541796) or a porous layer
containing hollow polymer particles (see, e.g., Japanese Patent No.
2726040) each having high cushion properties is formed between the
support and the receptor layer, is known. The methods have an
advantage that it is possible to prevent the image-receiving sheet
from wrinkling and curling that are often found in the method in
which a composite support made of a biaxially-oriented polyolefin
film containing microvoids is used, because a heat-insulating layer
can be formed on a base material by coating according to the
method. However, it is generally difficult to produce a uniform
smooth image-receiving sheet, often causing problems such as bad
image-transfer.
[0007] To solve the problems described above, an image-receiving
sheet having a heat insulation layer made of hollow polymer
particles and an organic solvent-resistant polymer as principal
components is disclosed (see, e.g., Japanese Patent No. 3226167).
However, the image-receiving sheet has not met a sufficient level.
In addition, a method in which a solution for forming an
intermediate layer is coated on a sheet-shaped base material and an
image-receiving sheet is formed while pressing the coated face to a
cast drum in forming an intermediate layer of a resin containing
hollow particles as the principal component on the sheet-shaped
base material, is disclosed (see, e.g., JP-A-5-8572). However,
although such a method is effective in giving sufficient
smoothness, it makes the production process more complicated and is
thus disadvantageous from the viewpoint of productivity.
[0008] In addition, the aforementioned method of forming a layer
containing hollow polymer particles between the support and the
receptor layer tends to cause surface defects by coating and thus
image defects, than the method of using a composite support made of
a biaxially-oriented polyolefin film containing microvoids.
SUMMARY OF THE INVENTION
[0009] The present invention resides in a heat-sensitive transfer
image-receiving sheet, comprising, on a support, at least one
receptor layer, and at least one heat insulation layer containing
hollow polymer particles which layer is provided between the
support and the receptor layer,
wherein the hollow polymer particles have an average particle
diameter of 0.3 to 1.0 .mu.m; and
wherein, in the hollow polymer particles, the ratio of the number
of bulky particles having a particle diameter of 10 .mu.m or more
is less than 1/5,000 of the total number of the hollow polymer
particles.
[0010] Further, the present invention resides in a method of
producing a heat-sensitive transfer image-receiving sheet,
comprising the steps of:
preparing hollow polymer particles having an average particle
diameter of 0.3 to 1.0 .mu.m,
removing bulky particles having a particle diameter of 10 .mu.m or
more contained in the hollow polymer particles, to a ratio of the
number of the bulky particles being less than 1/5,000 for the total
number of the hollow polymer particles, and
[0011] forming a heat-sensitive transfer image-receiving sheet that
has, on a support, at least one receptor layer, and at least one
heat insulation layer provided between the support and the receptor
layer, with using the hollow polymer particles, to form the heat
insulation layer.
[0012] Furthermore, the present invention resides in a method of
forming an image, which method comprises the steps of:
[0013] superposing the heat-sensitive transfer image-receiving
sheet upon a transfer material comprising a solid-phase ink layer,
and
[0014] applying a thermal energy from a thermal head of a thermal
transfer printer, and
[0015] forming an image on the receptor layer of the heat-sensitive
transfer image-receiving sheet.
[0016] Other and further features and advantages of the invention
will appear more fully from the following description.
DETAILED DESCRIPTION OF THE INVENTION
[0017] According to the present invention, there is provided the
following means:
[0018] (1) A heat-sensitive transfer image-receiving sheet,
comprising, on a support, at least one receptor layer, and at least
one heat insulation layer containing hollow polymer particles which
layer is provided between the support and the receptor layer,
wherein the hollow polymer particles have an average particle
diameter of 0.3 to 1.0 .mu.m; and
wherein, in the hollow polymer particles, the ratio of the number
of bulky particles having a particle diameter of 10 .mu.m or more
is less than 1/5,000 for the total number of the hollow polymer
particles.
[0019] (2) The heat-sensitive transfer image-receiving sheet as
described in (I), wherein the hollow polymer particles are
non-foaming type hollow particles of a type which has a hollow
(void) formed by vaporization of a dispersion medium inside of a
capsule wall of each particle, after application and drying of a
coating solution thereof.
(3) The heat-sensitive transfer image-receiving sheet as described
in (1) or (2), wherein the heat insulation layer further contains a
water-soluble polymer.
(4) The heat-sensitive transfer image-receiving sheet as described
in (3), wherein the water-soluble polymer is a gelatin and/or a
polyvinyl alcohol.
(5) The heat-sensitive transfer image-receiving sheet as described
in any one of (1) to (4), wherein the receptor layer contains at
least one kind of polymer having a repeating unit derived from
vinyl chloride.
(6) The heat-sensitive transfer image-receiving sheet as described
in any one of (1) to (5), wherein the heat insulation layer is
formed on the support by a method of using an aqueous coating
solution.
(7) The heat-sensitive transfer image-receiving sheet as described
in any one of (1) to (6), wherein the receptor layer and the heat
insulation layer are applied by a simultaneous multilayer
coating.
[0020] (8) The heat-sensitive transfer image-receiving sheet as
described in any one of (1) to (7), wherein the support comprises a
base paper (base sheet) and a polyolefin resin layer that is
provided on both side or at least on the side of the base paper to
which the receptor layer is provided.
(9) A method of producing a heat-sensitive transfer image-receiving
sheet, comprising the steps of:
preparing hollow polymer particles having an average particle
diameter of 0.3 to 1.0 .mu.m,
removing bulky particles having a particle diameter of 10 .mu.m or
more contained in the hollow polymer particles, to a ratio of the
number of the bulky particles being less than 1/5,000 for the total
number of the hollow polymer particles, and
[0021] forming a heat-sensitive transfer image-receiving sheet that
has, on a support, at least one receptor layer, and at least one
heat insulation layer provided between the support and the receptor
layer, with using the hollow polymer particles, to form the heat
insulation layer.
(10) A method of forming an image, which method comprises the steps
of:
[0022] superposing the heat-sensitive transfer image-receiving
sheet as described in any one of (1) to (8) upon a transfer
material comprising a solid-phase ink layer, and
[0023] applying a thermal energy from a thermal head of a thermal
transfer printer, and
[0024] forming an image on the receptor layer of the heat-sensitive
transfer image-receiving sheet.
[0025] After intensive studies, the inventors have found that the
frequency of the surface defects generated on a heat-sensitive
transfer image-receiving sheet was increased significantly by the
presence of bulky particles of a particular size or more derived
from a hollow polymer (the fact that bulky particles cause the
surface defects was quite unexpected, because bulky particles were
seldom found in the region where the surface defect was actually
generated). The present invention was made based on the
finding.
[0026] The present invention is explained in detail below.
[0027] The heat-sensitive transfer image-receiving sheet of the
present invention is provided with at least one dye-receiving layer
(receptor layer) and at least one heat insulation layer on a
support. It is preferable to form an undercoat layer between the
receptor layer and the support. As the undercoat layer, for
example, a white background control layer, a charge control layer,
an adhesive layer and a primer layer can be formed. Also, a
releasing layer may be formed as an outermost layer which can be
contacted with a transfer material. It is preferable that a curling
control layer, a writing layer, or a charge-control layer be formed
on the backside of the support. Each of these layers is applied
using a usual method such as a roll coating, a bar coating, a
gravure coating, a gravure reverse coating, a dye coating, a slide
coating and a curtain coating. In practicing the present invention,
a method capable of conducting a simultaneous multi-layer coating,
such as the slide coating and the curtain coating, is
preferable.
[0028] The receptor layer, the heat insulation layer, and other
layer(s) may be formed separately, or any layers may be formed
simultaneously by multi-layer coating, but all the layers on the
same surface are preferably formed simultaneously by multi-layer
coating.
(Receptor Layer)
[0029] The receptor layer performs functions of receiving dyes
transferred from an ink sheet and retaining images formed. The
image-receiving sheet of the present invention has at least one
receptor layer preferably containing at least one thermoplastic
receiving polymer that can receive a dye.
[0030] The receiving polymer is preferably used, as it is dispersed
in a water-soluble dispersion medium as a latex polymer. In
addition, the receptor layer preferably contains a water-soluble
polymer together with the latex polymer. Co-presence of the latex
polymer and the water-soluble polymer allows presence of the
water-soluble polymer, which is hardly dyable, among the latex
polymers and prevents diffusion of the dye fixed on the latex
polymer, and consequently, reduces changes in the color sharpness
of the receptor layer with the lapse of time and forms a recorded
image smaller in changes for its transferred image quality with the
lapse of time.
[0031] The receptor layer may contain, in addition to the latex
polymer of the receiving polymer, another latex polymer having a
different function, for example, for the purpose of adjusting the
elastic modulus of the film.
<Latex Polymer>
[0032] The latex polymer that can be used in the present invention
is explained.
[0033] In the heat-sensitive transfer image-receiving sheet of the
present invention, the latex polymer that can be used in the
receptor layer is a dispersion in which a water-insoluble
hydrophobic polymer is dispersed as fine particles in a
water-soluble dispersion medium. As the latex polymer, there is no
particular limitation, in so far as the latex polymer uses at least
one thermoplastic polymer capable of receiving dyes transferred
from a transfer material. The latex polymer that can be used in the
present invention includes preferably at least one latex polymer
containing at least vinyl chloride as a monomer unit, i.e., a latex
polymer having a repeating unit derived from vinyl chloride.
Multiple kinds of different latex polymers may be used in
combination.
[0034] The dispersed state may be one in which polymer is
emulsified in a dispersion medium, one in which polymer underwent
emulsion polymerization, one in which polymer underwent micelle
dispersion, one in which polymer molecules partially have a
hydrophilic structure and thus the molecular chains themselves are
dispersed in a molecular state, or the like. Latex polymers are
described in "Gosei Jushi Emulsion (Synthetic Resin Emulsion)",
compiled by Taira Okuda and Hiroshi Inagaki, issued by Kobunshi
Kanko Kai (1978); "Gosei Latex no Oyo (Application of Synthetic
Latex)", compiled by Takaaki Sugimura, Yasuo Kataoka, Souichi
Suzuki, and Keishi Kasahara, issued by Kobunshi Kanko Kai (1993);
Soichi Muroi, "Gosei Latex no Kagaku (Chemistry of Synthetic
Latex)", issued by Kobunshi Kanko Kai (1970); Yoshiaki Miyosawa
(supervisor) "Suisei Coating-Zairyo no Kaihatsu to Oyo (Development
and Application of Aqueous Coating Material)", issued by CMC
Publishing Co., Ltd. (2004) and JP-A-64-538, and so forth.
[0035] The dispersed particles preferably have a mean average
particle size (diameter) of about 1 to 50,000 nm, more preferably
about 5 to 1,000 nm.
[0036] The particle size distribution of the dispersed particles is
not particularly limited, and the particles may have either wide
particle-size distribution or monodispersed particle-size
distribution.
[0037] The latex polymer that can be used in the present invention
may be latex of the so-called core/shell type, other than ordinary
latex polymer of a uniform structure. When using a core/shell type
latex polymer, it is preferred in some cases that the core and the
shell have different glass transition temperatures. The glass
transition temperature (Tg) of the latex polymer that can be used
in the present invention is preferably -30.degree. C. to
100.degree. C., more preferably 0.degree. C. to 80.degree. C.,
further more preferably 10.degree. C. to 70.degree. C., and
especially preferably 15.degree. C. to 60.degree. C.
[0038] The glass transition temperature (Tg) is calculated
according to the following equation: 1/Tg=.SIGMA.(Xi/Tgi) wherein,
assuming that the polymer is a copolymer composed of n monomers
from i=1 to i=n, Xi is a weight fraction of the i-th monomer
(.SIGMA.Xi=1) and Tgi is glass transition temperature (measured in
absolute temperature) of a homopolymer formed from the i-th
monomer. The symbol .SIGMA. means the sum of i=1 to i=n. The value
of the glass transition temperature of a homopolymer formed from
each monomer (Tgi) is adopted from J. Brandrup and E. H. Immergut,
"Polymer Handbook, 3rd. Edition", Wiley-Interscience (1989).
[0039] In the receptor layer of the present invention, as a
preferable embodiment of the latex polymer comprising a polymer
having repeating units derived from vinyl chloride, there can be
preferably used polyvinyl chlorides, a copolymer comprising vinyl
chloride unit, such as a vinyl chloride-vinyl acetate copolymer and
a vinyl chloride acrylate copolymer. In case of the copolymer, the
vinyl chloride unit in molar ratio is preferably in the range of
from 50% to 95%. These polymers may be straight-chain, branched, or
cross-linked polymers, the so-called homopolymers obtained by
polymerizing single type of monomers, or copolymers obtained by
polymerizing two or more types of monomers. In the case of the
copolymers, these copolymers may be either random copolymers or
block copolymers. The molecular weight of each of these polymers is
preferably 5,000 to 1,000,000, and further preferably 10,000 to
500,000 in terms of number average molecular weight. Polymers
having excessively small molecular weight impart insufficient
dynamic strength to the layer containing the latex, and polymers
having excessively large molecular weight bring about poor filming
ability, and therefore both cases are not preferable. Crosslinkable
latex polymers are also preferably used.
[0040] The latex polymer comprising a copolymer having repeating
units derived from vinyl chloride that can be used in the present
invention is commercially available, and polymers described below
may be utilized. Examples thereof include G351 and G576 (trade
names, manufactured by Nippon Zeon Co., Ltd.); VINYBLAN 240, 270,
277, 375, 386, 609, 550, 601, 602, 630, 660, 671, 683, 680, 680S,
681N, 685R, 277, 380, 381, 410, 430, 432, 860, 863, 865, 867, 900,
900GT, 938 and 950 (trade names, manufactured by Nissin Chemical
Industry Co., Ltd.).
[0041] The latex polymer in the other structure that can be used in
combination with the latex polymer comprising vinyl chloride as a
monomer unit is not particularly limited, but hydrophobic polymers
such as acrylic-series polymers, polyesters, rubbers (e.g., SBR
resins), polyurethanes, polyvinyl chlorides, polyvinyl acetates,
polyvinylidene chlorides, and polyolefins, are preferably used.
These polymers may be straight-chain, branched, or cross-linked
polymers, the so-called homopolymers obtained by polymerizing
single type of monomers, or copolymers obtained by polymerizing two
or more types of monomers. In the case of the copolymers, these
copolymers may be either random copolymers or block copolymers. The
molecular weight of each of these polymers is preferably 5,000 to
1,000,000, and further preferably 10,000 to 500,000 in terms of
number average molecular weight. A polymer having an excessively
small molecular weight imparts insufficient dynamic strength to a
layer containing a latex of the polymer, and a polymer having an
excessively large molecular weight brings about poor filming
ability, and therefore both cases are not preferable. Crosslinkable
polymer latexes are also preferably used.
[0042] No particular limitation is imposed on a monomer to be used
in synthesizing the latex polymer having the other structure that
can be used in combination with the above-described latex polymer
in the present invention, and the following monomer groups (a) to
(j) may be preferably used as those polymerizable in a usual
radical polymerization or ion polymerization method. These monomers
may be selected singly or combined freely to synthesize the latex
polymer.
--Monomer Groups (a) to (j)--
(a) Conjugated dienes: 1,3-pentadiene, isoprene,
1-phenyl-1,3-butadiene, 1-.alpha.-naphthyl-1,3-butadiene,
1-.beta.-naphthyl-1,3-butadiene, cyclopentadiene, etc.
(b) Olefins: ethylene, propylene, vinyl chloride, vinylidene
chloride, 6-hydroxy-1-hexene, 4-pentenoic acid, methyl 8-nonenate,
vinylsulfonic acid, trimethylvinylsilane, trimethoxyvinylsilane,
1,4-divinylcyclohexane, 1,2,5-trivinylcyclohexane, etc.
[0043] (c) .alpha.,.beta.-unsaturated carboxylates: alkyl
acrylates, such as methyl acrylate, ethyl acrylate, butyl acrylate,
cyclohexyl acrylate, 2-ethylhexyl acrylate, and dodecyl acrylate;
substituted alkyl acrylates, such as 2-chloroethyl acrylate, benzyl
acrylate, and 2-cyanoethyl acrylate; alkyl methacrylates, such as
methyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate,
and dodecyl methacrylate; substituted alkyl methacrylates, such as
2-hydroxyethyl methacrylate, glycidyl methacrylate, glycerin
monomethacrylate, 2-acetoxyethyl methacrylate, tetrahydrofurfuryl
methacrylate, 2-methoxyethyl methacrylate, polypropylene glycol
monomethacrylates (mole number of added polyoxypropylene=2 to 100),
3-N,N-dimethylaminopropyl methacrylate,
chloro-3-N,N,N-trimethylammoniopropyl methacrylate, 2-carboxyethyl
methacrylate, 3-sulfopropyl methacrylate, 4-oxysulfobutyl
methacrylate, 3-trimethoxysilylpropyl methacrylate, allyl
methacrylate, and 2-isocyanatoethyl methacrylate; derivatives of
unsaturated dicarboxylic acids, such as monobutyl maleate, dimethyl
maleate, monomethyl itaconate, and dibutyl itaconate;
multifunctional esters, such as ethylene glycol diacrylate,
ethylene glycol dimethacrylate, 1,4-cyclohexane diacrylate,
pentaerythritol tetramethacrylate, pentaerythritol triacrylate,
trimethylolpropane triacrylate, trimethylolethane triacrylate,
dipentaerythritol pentamethacrylate, pentaerythritol hexaacrylate,
and 1,2,4-cyclohexane tetramethacrylate; etc.
[0044] (d) .alpha.,.beta.-unsaturated carboxylic amides:
acrylamide, methacrylamide, N-methylacrylamide,
N,N-dimethylacrylamide, N-methyl-N-hydroxyethylmethacrylamide,
N-tert-butylacrylamide, N-tert-octylmethacrylamide,
N-cyclohexylacrylamide, N-phenylacrylamide,
N-(2-acetoacetoxyethyl)acrylamide, N-acryloylmorpholine, diacetone
acrylamide, itaconic diamide, N-methylmaleimide,
2-acrylamidemethylpropane sulfonic acid, methylenebisacrylamide,
dimethacryloylpiperazine, etc.
(e) Unsaturated nitriles: acrylonitrile, methacrylonitrile,
etc.
[0045] (f) Styrene and derivatives thereof: styrene, vinyltoluene,
p-tert-butylstyrene, vinylbenzoic acid, methyl vinylbenzoate,
.alpha.-methylstyrene, p-chloromethylstyrene, vinylnaphthalene,
p-hydroxymethylstyrene, sodium p-styrenesulfonate, potassium
p-styrenesulfinate, p-aminomethylstyrene, 1,4-divinylbenzene,
etc.
(g) Vinyl ethers: methyl vinyl ether, butyl vinyl ether,
methoxyethyl vinyl ether, etc.
(h) Vinyl esters: vinyl acetate, vinyl propionate, vinyl benzoate,
vinyl salicylate, vinyl chloroacetate, etc.
(i) .alpha.,.beta.-unsaturated carboxylic acids and salts thereof:
acrylic acid, methacrylic acid, itaconic acid, maleic acid, sodium
acrylate, ammonium methacrylate, potassium itaconate, etc.
(j) Other polymerizable monomers: N-vinylimidazole,
4-vinylpyridine, N-vinylpyrrolidone, 2-vinyloxazoline,
2-isopropenyloxazoline, divinylsulfone, etc.
[0046] Latex polymers that can be used in combination are also
commercially available, and polymers described below may be
utilized.
[0047] Examples of the acrylic-series polymers include Cevian
A-4635, 4718, and 4601 (trade names, manufactured by Daicel
Chemical Industries); Nipol Lx811, 814, 821, 820, 855 (P-17: Tg
36.degree. C.), and 857.times.2 (P-18: Tg 43.degree. C.) (trade
names, manufactured by Nippon Zeon Co., Ltd.); Voncoat R3370 (P-19:
Tg 25.degree. C.), and 4280 (P-20: Tg 15.degree. C.) (trade names,
manufactured by Dai-Nippon Ink & Chemicals, Inc.); Julimer
ET-410 (P-21: Tg 44.degree. C.) (trade name, manufactured by Nihon
Junyaku K.K.); AE116 (P-22: Tg 50.degree. C.), AE119 (P-23: Tg
55.degree. C.), AE121 (P-24: Tg 58.degree. C.), AE125 (P-25: Tg
60.degree. C.), AE134 (P-26: Tg 48.degree. C.), AE137 (P-27: Tg
48.degree. C.), AE140 (P-28: Tg 53.degree. C.), and AE173 (P-29: Tg
60.degree. C.) (trade names, manufactured by JSR Corporation); Aron
A-104 (P-30: Tg 45.degree. C.) (trade name, manufactured by
Toagosei Co., Ltd.); NS-600.times., and NS-620X (trade names,
manufactured by Takamatsu Yushi K.K.); VINYBLAN 2580, 2583, 2641,
2770, 2770H, 2635, 2886, 5202C, and 2706 (trade names, manufactured
by Nissin Chemical Industry Co., Ltd.).
[0048] Examples of the polyesters include FINETEX ES650, 611, 675,
and 850 (trade names, manufactured by Dainippon Ink and Chemicals,
Incorporated); WD-size, and WMS (trade names, manufactured by
Eastman Chemical Ltd.); A-110, A-15GE, A-120, A-121, A-124GP,
A-124S, A-160P, A-210, A-215GE, A-510, A-513E, A-515GE, A-520,
A-610, A-613, A-615GE, A-620, WAC-10, WAC-15, WAC-17XC, WAC-20,
S-110, S-110EA, S-111SL, S-120, S-140, S-140A, S-250, S-252G,
S-250S, S-320, S-680, DNS-63P, NS-122L, NS-122LX, NS-244LX,
NS-140L, NS-141LX, and NS-282LX (trade names, manufactured by
Takamatsu Yushi K.K.); Aronmelt PES-1000 series, and PES-2000
series (trade names, manufactured by Toagosei Co., Ltd.); Bironal
MD-1100, MD-1200, MD-1220, MD-1245, MD-1250, MD-1335, MD-1400,
MD-1480, MD-1500, MD-1930, and MD-1985 (trade names, manufactured
by Toyobo Co., Ltd.); and Ceporjon ES (trade name, manufactured by
Sumitomo Seika Chemicals Co., Ltd.).
[0049] Examples of the polyurethanes include HYDRAN AP10, AP20,
AP30, AP40, and 101H, Vondic 1320NS and 1610NS (trade names,
manufactured by Dainippon Ink and Chemicals, Incorporated); D-1000,
D-2000, D-6000, D-4000, and D-9000 (trade names, manufactured by
Dainichi Seika Color & Chemicals Mfg. Co., Ltd.); NS-155X,
NS-310A, NS-310X, and NS-311X (trade names, manufactured by
Takamatsu Yushi K.K.); Elastron (trade name, manufactured by
Dai-ichi Kogyo Seiyaku Co., Ltd.).
[0050] Examples of the rubbers include LACSTAR 7310K, 3307B, 4700H,
and 7132C (trade names, manufactured by Dainippon Ink &
Chemicals Incorporated); Nipol Lx416, LX410, LX430, LX435, LX110,
LX415A, LX438C, 2507H, LX303A, LX407BP series, V1004, and MH5055
(trade names, manufactured by Nippon Zeon Co., Ltd.).
[0051] Examples of the polyolefins include Chemipearl S120, SA100,
and V300 (P-40: Tg 80.degree. C.) (trade names, manufactured by
Mitsui Petrochemical); Voncoat 2830, 2210, and 2960 (trade names,
manufactured by Dainippon Ink and Chemicals, Incorporated);
Zaikusen and Ceporjon G (trade names, manufactured by Sumitomo
Seika Chemicals Co., Ltd.).
[0052] Examples of the copolymer nylons include Ceporjon PA (trade
name, manufactured by Sumitomo Seika Chemicals Co., Ltd.).
[0053] Examples of the polyvinyl acetates include VINYBLAN 1080,
1082, 1085W, 1108W, 1108S, 1563M, 1566, 1570, 1588C, A22J7-F2,
1128C, 1137, 1138, A20J2, A23J1, A23J1, A23K1, A23P2E, A68J1N,
1086A, 1086, 1086D, 1108S, 1187, 1241LT, 1580N, 1083, 1571, 1572,
1581, 4465, 4466, 4468W, 4468S, 4470, 4485LL, 4495LL, 1023, 1042,
1060, 1060S, 1080M, 1084W, 1084S, 1096, 1570K, 1050, 1050S, 3290,
1017AD, 1002, 1006, 1008, 1107L, 1225, 1245L, GV-6170, GV-6181,
4468W, and 4468S (trade names, manufactured by Nisshin Chemical
Industry Co., Ltd.).
[0054] These latex polymers may be used singly, or two or more of
these polymers may be blended, if necessary.
[0055] In the receptor layer for use in the present invention, a
ratio of the latex polymer comprising a component of vinyl chloride
is preferably 50 mass % or more of the whole solid content in the
layer.
[0056] The glass transition temperature (Tg) of the latex polymer
having the other structure that can be used in combination with the
latex polymer comprising vinyl chloride as a monomer unit is
preferably in the range of -30.degree. C. to 70.degree. C., more
preferably -10.degree. C. to 50.degree. C., still more preferably
0.degree. C. to 40.degree. C., in view of film-forming properties
(brittleness for working) and image preservability. A blend of two
or more types of polymers can be used as the binder. When a blend
of two or more polymers is used, the average Tg obtained by summing
up the Tg of each polymer weighted by its proportion, is preferably
within the foregoing range. Also, when phase separation occurs or
when a core-shell structure is adopted, the weighted average Tg is
preferably within the foregoing range.
[0057] The latex polymer that can be used in the present invention
preferably has a minimum film-forming temperature (MFT) of from -30
to 90.degree. C., more preferably from 0 to 70.degree. C. In order
to control the minimum film-forming temperature, a film-forming aid
may be added. The film-forming aid is also called a temporary
plasticizer, and it is an organic compound (usually an organic
solvent) that reduces the minimum film-forming temperature of a
latex polymer. It is described in, for example, Souichi Muroi,
"Gosei Latex no Kagaku (Chemistry of Synthetic Latex)", issued by
Kobunshi Kanko Kai (1970). Preferable examples of the film-forming
aid are listed below, but the compounds that can be used in the
present invention are not limited to the following specific
examples.
[0058] Z-1: Benzyl alcohol
[0059] Z-2: 2,2,4-Trimethylpentanediol-1,3-monoisobutyrate
[0060] Z-3: 2-Dimethylaminoethanol
[0061] Z-4: Diethylene glycol
[0062] The latex polymer that can be used in the present invention
can be easily obtained by a solution polymerization method, a
suspension polymerization method, an emulsion polymerization
method, a dispersion polymerization method, an anionic
polymerization method, a cationic polymerization method, or the
like. Above all, an emulsion polymerization method in which the
polymer is obtained as a latex is the most preferable. Also, a
method is preferable in which the polymer is prepared in a
solution, and the solution is neutralized, or an emulsifier is
added to the solution, to which water is then added, to prepare an
aqueous dispersion by forced stirring. For example, an emulsion
polymerization method comprises conducting polymerization under
stirring at about 30.degree. C. to about 100.degree. C. (preferably
60.degree. C. to 90.degree. C.) for 3 to 24 hours by using water or
a mixed solvent of water and a water-miscible organic solvent (such
as methanol, ethanol, or acetone) as a dispersion medium, a monomer
mixture in an amount of 5 mass % to 150 mass % based on the amount
of the dispersion medium, an emulsifier and a polymerization
initiator. Various conditions such as the dispersion medium, the
monomer concentration, the amount of initiator, the amount of
emulsifier, the amount of dispersant, the reaction temperature, and
the method for adding monomers are suitably determined considering
the type of the monomers to be used. Furthermore, it is preferable
to use a dispersant when necessary.
[0063] Generally, the emulsion polymerization method can be
conducted according to the disclosures of the following documents:
"Gosei Jushi Emarujon (Synthetic Resin Emulsions)" (edited by Taira
Okuda and Hiroshi Inagaki and published by Kobunshi Kankokai
(1978)); "Gosei Ratekkusu no Oyo (Applications of
Synthetic-Latexes)" (edited by Takaaki Sugimura, Yasuo Kataoka,
Soichi Suzuki, and Keiji Kasahara and published by Kobunshi
Kankokai (1993)); and "Gosei Ratekkusu no Kagaku (Chemistry of
Synthetic Latexes)" (edited by Soichi Muroi and published by
Kobunshi Kankokai (1970)). The emulsion polymerization method for
synthesizing the latex polymer that can be used in the present
invention may be a batch polymerization method, a monomer
(continuous or divided) addition method, an emulsion addition
method, or a seed polymerization method. The emulsion
polymerization method is preferably a batch polymerization method,
a monomer (continuous or divided) addition method, or an emulsion
addition method in view of the productivity of latex.
[0064] The polymerization initiator may be any polymerization
initiator having radical generating ability. The polymerization
initiator to be used may be selected from inorganic peroxides such
as persulfates and hydrogen peroxide, peroxides described in the
organic peroxide catalogue of NOF Corporation, and azo compounds as
described in the azo polymerization initiator catalogue of Wako
Pure Chemical Industries, Ltd. Among them, water-soluble peroxides
such as persulfates and water-soluble azo compounds as described in
the azo polymerization initiator catalogue of Wako Pure Chemical
Industries, Ltd. are preferable; ammonium persulfate, sodium
persulfate, potassium persulfate, azobis(2-methylpropionamidine)
hydrochloride, azobis(2-methyl-N-(2-hydroxyethyl)propionamide), and
azobiscyanovaleric acid are more preferable; and peroxides such as
ammonium persulfate, sodium persulfate, and potassium persulfate
are especially preferable from the viewpoints of image
preservability, solubility, and cost.
[0065] The amount of the polymerization initiator to be added is,
based on the total amount of monomers, preferably 0.3 mass % to 2.0
mass %, more preferably 0.4 mass % to 1.75 mass %, and especially
preferably 0.5 mass % to 1.5 mass %.
[0066] The polymerization emulsifier to be used may be selected
from anionic surfactants, nonionic surfactants, cationic
surfactants, and ampholytic surfactants. Among them, anionic
surfactants are preferable from the viewpoints of dispersibility
and image preservability. Sulfonic acid type anionic surfactants
are more preferable because polymerization stability can be ensured
even with a small addition amount and they have resistance to
hydrolysis. Long chain alkyldiphenyl ether disulfonic acid salts
(whose typical example is PELEX SS-H (trade name) manufactured by
Kao Corporation) are still more preferable, and low electrolyte
types such as PIONIN A-43-S (trade name, manufactured by Takemoto
Oil & Fat Co., Ltd.) are especially preferable.
[0067] The amount of sulfonic acid type anionic surfactant as the
polymerization emulsifier is preferably 0.1 mass % to 10.0 mass %,
more preferably 0.2 mass % to 7.5 mass %, and especially preferably
0.3 mass % to 5.0 mass %, based on the total amount of
monomers.
[0068] It is preferable to use a chelating agent in synthesizing
the latex polymer that can be used in the present invention. The
chelating agent is a compound capable of coordinating (chelating) a
polyvalent ion such as metal ion (e.g., iron ion) or alkaline earth
metal ion (e.g., calcium ion), and examples of the chelate compound
which can be used include the compounds described in JP-B-6-8956
("JP-B" means examined Japanese patent publication), U.S. Pat. No.
5,053,322, JP-A-4-73645, JP-A-4-127145, JP-A-4-247073,
JP-A-4-305572, JP-A-6-11805, JP-A-5-173312, JP-A-5-66527,
JP-A-5-158195, JP-A-6-118580, JP-A-6-110168, JP-A-6-161054,
JP-A-6-175299, JP-A-6-214352, JP-A-7-114161, JP-A-7-114154,
JP-A-7-120894, JP-A-7-199433, JP-A-7-306504, JP-A-9-43792,
JP-A-8-314090, JP-A-10-182571, JP-A-10-182570, and
JP-A-11-190892.
[0069] Preferred examples of the chelating agent include inorganic
chelate compounds (e.g., sodium tripolyphosphate, sodium
hexametaphosphate, sodium tetrapolyphosphate), aminopolycarboxylic
acid-based chelate compounds (e.g., nitrilotriacetic acid,
ethylenediaminetetraacetic acid), organic phosphonic acid-based
chelate compounds (e.g., compounds described in Research
Disclosure, No. 18170, JP-A-52-102726, JP-A-53-42730,
JP-A-56-97347, JP-A-54-121127, JP-A-55-4024, JP-A-55-4025,
JP-A-55-29883, JP-A-55-126241, JP-A-55-65955, JP-A-55-65956,
JP-A-57-179843, JP-A-54-61125, and West German Patent No. 1045373),
polyphenol-based chelating agents, and polyamine-based chelate
compounds, with aminopolycarboxylic acid derivatives being
particularly preferred.
[0070] Preferred examples of the aminopolycarboxylic acid
derivative include the compounds shown in the Table attached to
"EDTA (--Complexane no Kagaku--) (EDTA--Chemistry of
Complexane--)", Nankodo (1977). In these compounds, a part of the
carboxyl groups may be substituted by an alkali metal salt such as
sodium or potassium or by an ammonium salt. More preferred examples
of the aminopolycarboxylic acid derivative include iminodiacetic
acid, N-methyliminodiacetic acid, N-(2-aminoethyl)iminodiacetic
acid, N-(carbamoylmethyl)iminodiacetic acid, nitrilotriacetic acid,
ethylenediamine-N,N'-diacetic acid,
ethylenediamine-N,N'-di-.alpha.-propionic acid,
ethylenediamine-N,N'-di-.beta.-propionic acid,
N,N'-ethylene-bis(.alpha.-o-hydroxyphenyl)glycine,
N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid,
ethylenediamine-N,N'-diacetic acid-N,N'-diacetohydroxamic acid,
N-hydroxyethylethylenediamine-N,N',N'-triacetic acid,
ethylenediamine-N,N,N',N'-tetraacetic acid,
1,2-propylenediamine-N,N,N',N'-tetraacetic acid,
d,l-2,3-diaminobutane-N,N,N',N'-tetraacetic acid,
meso-2,3-diaminobutane-N,N,N',N'-tetraacetic acid,
1-phenylethylenediamine-N,N,N',N'-tetraacetic acid,
d,l-1,2-diphenylethylenediamine-N,N,N',N'-tetraacetic acid,
1,4-diaminobutane-N,N,N',N'-tetraacetic acid,
trans-cyclobutane-1,2-diamine-N,N,N',N'-tetraacetic acid,
trans-cyclopentane-1,2-diamine-N,N,N',N'-tetraacetic acid,
trans-cyclohexane-1,2-diamine-N,N,N',N'-tetraacetic acid,
cis-cyclohexane-1,2-diamine-N,N,N',N'-tetraacetic acid,
cyclohexane-1,3-diamine-N,N,N',N'-tetraacetic acid,
cyclohexane-1,4-diamine-N,N,N',N'-tetraacetic acid,
o-phenylenediamine-N,N,N',N'-tetraacetic acid,
cis-1,4-diaminobutene-N,N,N',N'-tetraacetic acid,
trans-1,4-diaminobutene-N,N,N',N'-tetraacetic acid,
.alpha.,.alpha.'-diamino-o-xylene-N,N,N',N'-tetraacetic acid,
2-hydroxy-1,3-propanediamine-N,N,N',N'-tetraacetic acid,
2,2'-oxy-bis(ethyliminodiacetic acid),
2,2'-ethylenedioxy-bis(ethyliminodiacetic acid),
ethylenediamine-N,N'-diacetic acid-N,N'-di-.alpha.-propionic acid,
ethylenediamine-N,N'-diacetic acid-N,N'-di-.beta.-propionic acid,
ethylenediamine-N,N,N',N'-tetrapropionic acid,
diethylenetriamine-N,N,N',N'',N''-pentaacetic acid,
triethylenetetramine-N,N,N',N'',N''',N'''-hexaacetic acid, and
1,2,3-triaminopropane-N,N,N',N'',N''',N'''-hexaacetic acid. In
these compounds, a part of the carboxyl groups may be substituted
by an alkali metal salt such as sodium or potassium or by an
ammonium salt.
[0071] The amount of the chelating agent to be added is preferably
0.01 mass % to 0.4 mass %, more preferably 0.02 mass % to 0.3 mass
%, and especially preferably 0.03 mass % to 0.15 mass %, based on
the total amount of monomers. When the addition amount of the
chelating agent is too small, metal ions entering during the
preparation of the latex polymer are not sufficiently trapped, and
the stability of the latex against aggregation is lowered, whereby
the coating properties become worse. When the amount is too large,
the viscosity of the latex increases, whereby the coating
properties are lowered.
[0072] In the preparation of the latex polymer that can be used in
the present invention, it is preferable to use a chain transfer
agent. As the chain transfer agent, ones described in Polymer
Handbook (3rd Edition) (Wiley-Interscience, 1989) are preferable.
Sulfur compounds are more preferable because they have high
chain-transfer ability and because the required amount is small.
Especially, hydrophobic mercaptane-based chain transfer agents such
as tert-dodecylmercaptane and n-dodecylmercaptane are
preferable.
[0073] The amount of the chain transfer agent to be added is
preferably 0.2 mass % to 2.0 mass %, more preferably 0.3 mass % to
1.8 mass %, and especially preferably 0.4 mass % to 1.6 mass %,
based on the total amount of monomers.
[0074] Besides the foregoing compounds, in the emulsion
polymerization, use can be made of additives, such as electrolytes,
stabilizers, thickeners, defoaming agents, antioxidants,
vulcanizers, antifreezing agents, gelling agents, and vulcanization
accelerators, as described, for example, in Synthetic Rubber
Handbook.
[0075] In the present invention, it is preferable to prepare the
latex polymer by applying an aqueous type coating solution and then
drying it. The "aqueous type" so-called here means that 60% by mass
or more of the solvent (dispersion medium) of the coating solution
is water. As a component other than water in the coating solution,
a water miscible organic solvent may be used, such as methyl
alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl
cellosolve, dimethylformamide, ethyl acetate, diacetone alcohol,
furfuryl alcohol, benzyl alcohol, diethylene glycol monoethyl
ether, and oxyethyl phenyl ether.
[0076] The latex polymer in the image-receiving sheet that can be
used in the present invention includes a state of a gel or dried
film formed by removing a part of solvents by drying after
coating.
<Water-Soluble Polymer>
[0077] The receptor layer preferably contains a water-soluble
polymer. Herein, "water-soluble polymer" means a polymer which
dissolves, in 100 g water at 20.degree. C., in an amount of
preferably 0.05 g or more, more preferably 0.1 g or more, further
preferably 0.5 g or more, and particularly preferably 1 g or more.
The water-soluble polymer which can be used in the present
invention is natural polymers (polysaccharide type, microorganism
type, and animal type), semi-synthetic polymers (cellulose-based,
starch-based, and alginic acid-based), and synthetic polymer type
(vinyl type and others); and synthetic polymers including polyvinyl
alcohols, and natural or semi-synthetic polymers using celluloses
derived from plant as starting materials, which will be explained
later, correspond to the water-soluble polymer usable in the
present invention. The latex polymers recited above are not
included in the water-soluble polymers which can be used in the
present invention. In the present invention, the water-soluble
polymer is also referred to as a binder, for differentiation from
the latex polymer described above.
[0078] Among the water-soluble polymers which can be used in the
present invention, the natural polymers and the semi-synthetic
polymers will be explained in detail. Specific examples include the
following polymers: plant type polysaccharides such as gum arabics,
.kappa.-carrageenans, -carrageenans, .lamda.-carrageenans, guar
gums (e.g. Supercol, manufactured by Squalon), locust bean gums,
pectins, tragacanths, corn starches (e.g. Purity-21, manufactured
by National Starch & Chemical Co.), and phosphorylated starches
(e.g. National 78-1898, manufactured by National Starch &
Chemical Co.); microbial type polysaccharides such as xanthan gums
(e.g. Keltrol T, manufactured by Kelco) and dextrins (e.g. Nadex
360, manufactured by National Starch & Chemical Co.); animal
type natural polymers such as gelatins (e.g. Crodyne B419,
manufactured by Croda), caseins, sodium chondroitin sulfates (e.g.
Cromoist CS, manufactured by Croda); cellulose-based polymers such
as ethylcelluloses (e.g. Cellofas WLD, manufactured by I.C.I.),
carboxymethylcelluloses (e.g. CMC, manufactured by Daicel),
hydroxyethylcelluloses (e.g. HEC, manufactured by Daicel),
hydroxypropylcelluloses (e.g. Klucel, manufactured by Aqualon),
methylcelluloses (e.g. Viscontran, manufactured by Henkel),
nitrocelluloses (e.g. Isopropyl Wet, manufactured by Hercules), and
cationated celluloses (e.g. Crodacel QM, manufactured by Croda);
starches such as phosphorylated starches (e.g. National 78-1898,
manufactured by National Starch & Chemical Co.); alginic
acid-based compounds such as sodium alginates (e.g. Keltone,
manufactured by Kelco) and propylene glycol alginates; and other
polymers such as cationated guar guns (e.g. Hi-care 1000,
manufactured by Alcolac) and sodium hyaluronates (e.g. Hyalure,
manufactured by Lifecare Biomedial) (all of the names are trade
names).
[0079] Gelatin is one of preferable embodiments in the present
invention. Gelatin having a molecular weight of from 10,000 to
1,000,000 may be used in the present invention. Gelatin that can be
used in the present invention may contain an anion such as Cl.sup.-
and SO.sub.4.sup.2-, or alternatively a cation such as Fe.sup.2+,
Ca.sup.2+, Mg.sup.2+, Sn.sup.2+, and Zn.sup.2+. Gelatin is
preferably added as an aqueous solution.
[0080] Among the water-soluble polymers which can be used in the
present invention, the synthetic polymers will be explained in
detail. Examples of the acryl type include sodium polyacrylates,
polyacrylic acid copolymers, polyacrylamides, polyacrylamide
copolymers, and polydiethylaminoethyl(meth)acrylate quaternary
salts or their copolymers. Examples of the vinyl type include
polyvinylpyrrolidones, polyvinylpyrrolidone copolymers, and
polyvinyl alcohols. Examples of the others include polyethylene
glycols, polypropylene glycols, polyisopropylacrylamides,
polymethyl vinyl ethers, polyethyleneimines, polystyrenesulfonic
acids or their copolymers, naphthalenesulfonic acid condensate
salts, polyvinylsulfonic acids or their copolymers, polyacrylic
acids or their copolymers, acrylic acid or its copolymers, maleic
acid copolymers, maleic acid monoester copolymers,
acryloylmethylpropanesulfonic acid or its copolymers,
polydimethyldiallylammonium chlorides or their copolymers,
polyamidines or their copolymers, polyimidazolines, dicyanamide
type condensates, epichlorohydrin/dimethylamine condensates,
Hofmann decomposed products of polyacrylamides, and water-soluble
polyesters (Plascoat Z-221, Z-446, Z-561, Z-450, Z-565, Z-850,
Z-3308, RZ-105, RZ-570, Z-730 and RZ-142 (all of these names are
trade names), manufactured by Goo Chemical Co., Ltd.).
[0081] In addition, highly-water-absorptive polymers, namely,
homopolymers of vinyl monomers having --COOM or --SO.sub.3M (M
represents a hydrogen atom or an alkali metal atom) or copolymers
of these vinyl monomers among them or with other vinyl monomers
(for example, sodium methacrylate, ammonium methacrylate, Sumikagel
L-5H (trade name) manufactured by Sumitomo Chemical Co., Ltd.) as
described in, for example, U.S. Pat. No. 4,960,681 and
JP-A-62-245260, may also be used.
[0082] Among the water-soluble synthetic polymers that can be used
in the present invention, polyvinyl alcohols are preferable. The
polyvinyl alcohols are explained in detail below.
[0083] Examples of completely saponificated polyvinyl alcohol
include PVA-105 [polyvinyl alcohol (PVA) content: 94.0 mass % or
more; degree of saponification: 98.5.+-.0.5 mol %; content of
sodium acetate: 1.5 mass % or less; volatile constituent: 5.0 mass
% or less; viscosity (4 mass %; 20.degree. C.): 5.6.+-.0.4 CPS];
PVA-110 [PVA content: 94.0 mass %; degree of saponification:
98.5.+-.0.5 mol %; content of sodium acetate: 1.5 mass %; volatile
constituent: 5.0 mass %; viscosity (4 mass %; 20.degree. C.):
11.0.+-.0.8 CPS]; PVA-117 [PVA content: 94.0 mass %; degree of
saponification: 98.5.+-.0.5 mol %; content of sodium acetate: 1.0
mass %; volatile constituent: 5.0 mass %; viscosity (4 mass %;
20.degree. C.): 28.0.+-.3.0 CPS]; PVA-117H [PVA content: 93.5 mass
%; degree of saponification: 99.6.+-.0.3 mol %; content of sodium
acetate: 1.85 mass %; volatile constituent: 5.0 mass %; viscosity
(4 mass %; 20.degree. C.): 29.0.+-.3.0 CPS]; PVA-120 [PVA content:
94.0 mass %; degree of saponification: 98.5.+-.0.5 mol %; content
of sodium acetate: 1.0 mass %; volatile constituent: 5.0 mass %;
viscosity (4 mass %; 20.degree. C.): 39.5.+-.4.5 CPS]; PVA-124 [PVA
content: 94.0 mass %; degree of saponification: 98.5.+-.0.5 mol %;
content of sodium acetate: 1.0 mass %; volatile constituent: 5.0
mass %; viscosity (4 mass %; 20.degree. C.): 60.0.+-.6.0 CPS];
PVA-124H [PVA content: 93.5 mass %; degree of saponification:
99.6.+-.0.3 mol %; content of sodium acetate: 1.85 mass %; volatile
constituent: 5.0 mass %; viscosity (4 mass %; 20.degree. C.):
61.0.+-.6.0 CPS]; PVA-CS [PVA content: 94.0 mass %; degree of
saponification: 97.5.+-.0.5 mol %; content of sodium acetate: 1.0
mass %; volatile constituent: 5.0 mass %; viscosity (4 mass %;
20.degree. C.): 27.5.+-.3.0 CPS]; PVA-CST [PVA content: 94.0 mass
%; degree of saponification: 96.0.+-.0.5 mol %; content of sodium
acetate: 1.0 mass %; volatile constituent: 5.0 mass %; viscosity (4
mass %; 20.degree. C.): 27.0.+-.3.0 CPS]; and PVA-HC [PVA content:
90.0 mass %; degree of saponification: 99.85 mol % or more; content
of sodium acetate: 2.5 mass %; volatile constituent: 8.5 mass %;
viscosity (4 mass %; 20.degree. C.): 25.0.+-.3.5 CPS] (all trade
names, manufactured by Kuraray Co., Ltd.), and the like.
[0084] Examples of partially saponificated polyvinyl alcohol
include PVA-203 [PVA content: 94.0 mass %; degree of
saponification: 88.0.+-.1.5 mol %; content of sodium acetate: 1.0
mass %; volatile constituent: 5.0 mass %; viscosity (4 mass %;
20.degree. C.): 3.4.+-.0.2 CPS]; PVA-204 [PVA content: 94.0 mass %;
degree of saponification: 88.0.+-.1.5 mol %; content of sodium
acetate: 1.0 mass %; volatile constituent: 5.0 mass %; viscosity (4
mass %; 20.degree. C.): 3.9.+-.0.3 CPS]; PVA-205 [PVA content: 94.0
mass %; degree of saponification: 88.0.+-.1.5 mol %; content of
sodium acetate: 1.0 mass %; volatile constituent: 5.0 mass %;
viscosity (4 mass %; 20.degree. C.): 5.0.+-.0.4 CPS]; PVA-210 [PVA
content: 94.0 mass %; degree of saponification: 88.0.+-.1.0 mol %;
content of sodium acetate: 1.0 mass %; volatile constituent: 5.0
mass %; viscosity (4 mass %; 20.degree. C.): 9.0.+-.1.0 CPS];
PVA-217 [PVA content: 94.0 mass %; degree of saponification:
88.0.+-.1.0 mol %; content of sodium acetate: 1.0 mass %; volatile
constituent: 5.0 mass %; viscosity (4 mass %; 20.degree. C.):
22.5.+-.2.0 CPS]; PVA-220 [PVA content: 94.0 mass %; degree of
saponification: 88.0.+-.1.0 mol %; content of sodium acetate: 1.0
mass %; volatile constituent: 5.0 mass %; viscosity (4 mass %;
20.degree. C.): 30.0.+-.3.0 CPS]; PVA-224 [PVA content: 94.0 mass
%; degree of saponification: 88.0.+-.1.5 mol %; content of sodium
acetate: 1.0 mass %; volatile constituent: 5.0 mass %; viscosity (4
mass %; 20.degree. C.): 44.0.+-.4.0 CPS]; PVA-228 [PVA content:
94.0 mass %; degree of saponification: 88.0.+-.1.5 mol %; content
of sodium acetate: 1.0 mass %; volatile constituent: 5.0 mass %;
viscosity (4 mass %; 20.degree. C.): 65.0.+-.5.0 CPS]; PVA-235 [PVA
content: 94.0 mass %; degree of saponification: 88.0.+-.1.5 mol %;
content of sodium acetate: 1.0 mass %; volatile constituent: 5.0
mass %; viscosity (4 mass %; 20.degree. C.): 95.0.+-.15.0 CPS];
PVA-217EE [PVA content: 94.0 mass %; degree of saponification:
88.0.+-.1.0 mol %; content of sodium acetate: 1.0 mass %; volatile
constituent: 5.0 mass %; viscosity (4 mass %; 20.degree. C.):
23.0.+-.3.0 CPS]; PVA-217E [PVA content: 94.0 mass %; degree of
saponification: 88.0.+-.1.0 mol %; content of sodium acetate: 1.0
mass %; volatile constituent: 5.0 mass %; viscosity (4 mass %;
20.degree. C.): 23.0.+-.3.0 CPS]; PVA-220E [PVA content: 94.0 mass
%; degree of saponification: 88.0.+-.1.0 mol %; content of sodium
acetate: 1.0 mass %; volatile constituent: 5.0 mass %; viscosity (4
mass %; 20.degree. C.): 31.0.+-.4.0 CPS]; PVA-224E [PVA content:
94.0 mass %; degree of saponification: 88.0.+-.1.0 mol %; content
of sodium acetate: 1.0 mass %; volatile constituent: 5.0 mass %;
viscosity (4 mass %; 20.degree. C.): 45.0.+-.5.0 CPS]; PVA-403 [PVA
content: 94.0 mass %; degree of saponification: 80.0.+-.1.5 mol %;
content of sodium acetate: 1.0 mass %; volatile constituent: 5.0
mass %; viscosity (4 mass %; 20.degree. C.): 3.1.+-.0.3 CPS];
PVA-405 [PVA content: 94.0 mass %; degree of saponification:
81.5.+-.1.5 mol %; content of sodium acetate: 1.0 mass %; volatile
constituent: 5.0 mass %; viscosity (4 mass %; 20.degree. C.):
4.8.+-.0.4 CPS]; PVA-420 [PVA content: 94.0 mass %; degree of
saponification: 79.5.+-.1.5 mol %; content of sodium acetate: 1.0
mass %; volatile constituent: 5.0 mass %]; PVA-613 [PVA content:
94.0 mass %; degree of saponification: 93.5.+-.1.0 mol %; content
of sodium acetate: 1.0 mass %; volatile constituent: 5.0 mass %;
viscosity (4 mass %; 20.degree. C.): 16.5.+-.2.0 CPS]; L-8 [PVA
content: 96.0 mass %; degree of saponification: 71.0.+-.1.5 mol %;
content of sodium acetate: 1.0 mass % (ash); volatile constituent:
3.0 mass %; viscosity (4 mass %; 20.degree. C.): 5.4.+-.0.4 CPS]
(all trade names, manufactured by Kuraray Co., Ltd.), and the
like.
[0085] The above values were measured in the manner described in
JIS K-6726-1977.
[0086] With respect to modified polyvinyl alcohols, those described
in Koichi Nagano, et al., "Poval", Kobunshi Kankokai, Inc. are
useful. The modified polyvinyl alcohols include polyvinyl alcohols
modified by cations, anions, --SH compounds, alkylthio compounds,
or silanols.
[0087] Examples of such modified polyvinyl alcohols (modified PVA)
include C polymers such as C-118, C-318, C-318-2A, and C-506 (all
being trade names of Kuraray Co., Ltd.); HL polymers such as
HIL-12E and HL-1203 (all being trade names of Kuraray Co., Ltd.);
HM polymers such as HM-03 and HM-N-03 (all being trade names of
Kuraray Co., Ltd.); K polymers such as KL-118, KL-318, KL-506,
KM-118T, and KM-618 (all being trade names of Kuraray Co., Ltd.); M
polymers such as M-115 (a trade name of Kuraray co., Ltd.); MP
polymers such as MP-102, MP-202, and MP-203 (all being trade names
of Kuraray Co., Ltd.); MPK polymers such as MPK-1, MPK-2, MPK-3,
MPK-4, MPK-5, and MPK-6 (all being trade names of Kuraray Co.,
Ltd.); R polymers such as R-1130, R-2105, and R-2130 (all being
trade names of Kuraray Co., Ltd.); and V polymers such as V-2250 (a
trade name of Kuraray Co., Ltd.).
[0088] The viscosity of polyvinyl alcohol can be adjusted or
stabilized by adding a trace amount of a solvent or an inorganic
salt to an aqueous solution of polyvinyl alcohol, and there can be
employed compounds described in the aforementioned reference
"Poval", Koichi Nagano et al., published by Kobunshi Kankokai, pp.
144-154. For example, a coated-surface quality can be improved by
an addition of boric acid, and the addition of boric acid is
preferable. The amount of boric acid added is preferably 0.01 to 40
mass % with respect to polyvinyl alcohol.
[0089] Preferred binders are transparent or semitransparent, and
generally colorless. Examples include natural resins, polymers and
copolymers; synthetic resins, polymers, and copolymers; and other
media that form films: for example, rubbers, polyvinyl alcohols,
hydroxyethyl celluloses, cellulose acetates, cellulose acetate
butylates, polyvinylpyrrolidones, starches, polyacrylic acids,
polymethyl methacrylates, polyvinyl chlorides, polymethacrylic
acids, styrene/maleic acid anhydride copolymers,
styrene/acrylonitrile copolymers, styrene/butadiene copolymers,
polyvinylacetals (e.g., polyvinylformals and polyvinylbutyrals),
polyesters, polyurethanes, phenoxy resins, polyvinylidene
chlorides, polyepoxides, polycarbonates, polyvinyl acetates,
polyolefins, cellulose esters, and polyamides. These media are
water-soluble.
[0090] In the present invention, preferred water-soluble polymers
are polyvinyl alcohols and gelatin, with gelatin being most
preferred.
[0091] The amount of the water-soluble polymer added to the
receptor layer is preferably from 1 to 25% by mass, more preferably
from 1 to 10% by mass based on the entire mass of the receptor
layer.
<Hardener>
[0092] As a crosslinking agent (compound capable of crosslinking,
for example, a water-soluble polymer), a hardener (hardening agent)
may be added in coating layers (e.g., the receptor layer, the heat
insulation layer, the undercoat layer) of the image-receiving
sheet.
[0093] The receptor layer preferably contains a crosslinking
agent.
[0094] A part or all of the above-mentioned water-soluble polymer
contained in the receptor layer has been preferably crosslinked
with the crosslinking agent.
[0095] Preferable examples of the hardener that can be used in the
present invention include H-1, 4, 6, 8, and 14 in JP-A-1-214845 in
page 17; compounds (H-1 to H-54) represented by one of the formulae
(VII) to (XII) in U.S. Pat. No. 4,618,573, columns 13 to 23;
compounds (H-1 to H-76) represented by the formula (6) in
JP-A-2-214852, page 8, the lower right (particularly, H-14); and
compounds described in Claim 1 in U.S. Pat. No. 3,325,287. Examples
of the hardening agent include hardening agents described, for
example, in U.S. Pat. No. 4,678,739, column 41, U.S. Pat. No.
4,791,042, JP-A-59-116655, JP-A-62-245261, JP-A-61-18942, and
JP-A-4-218044. More specifically, an aldehyde-series hardening
agent (formaldehyde, etc.), an aziridine-series hardening agent, an
epoxy-series hardening agent, a vinyl sulfone-series hardening
agent (N,N'-ethylene-bis(vinylsulfonylacetamido)ethane, etc.), an
N-methylol-series hardening agent (dimethylol urea, etc.), a boric
acid, a metaboric acid, or a polymer hardening agent (compounds
described, for example, in JP-A-62-234157), can be mentioned.
[0096] Preferable examples of the hardener include a
vinylsulfone-series hardener and chlorotriazines.
[0097] More preferable hardeners in the present invention are
compounds represented by the following Formula (B) or (C).
(CH.sub.2.dbd.CH--SO.sub.2).sub.n-L Formula (B)
(X--CH.sub.2--CH.sub.2--SO.sub.2).sub.n-L Formula (C)
[0098] In formulae (B) and (C), X represents a halogen atom, L
represents an organic linking group having n-valency. When the
compound represented by formula (B) or (C) is a low-molecular
compound, n denotes an integer from 1 to 4. When the compound
represented by formula (B) or (C) is a high-molecular (polymer)
compound, L represents an organic linking group containing a
polymer chain and n denotes an integer ranging from 10 to
1,000.
[0099] In the formulae (B) and (C), X is preferably a chlorine atom
or a bromine atom, and further preferably a bromine atom. n is an
integer from 1 to 4, preferably an integer from 2 to 4, more
preferably 2 or 3 and most preferably 2.
[0100] L represents an organic group having n-valency, and
preferably an aliphatic hydrocarbon group, an aromatic hydrocarbon
group or a heterocyclic group, provided that these groups may be
combined through an ether bond, ester bond, amide bond, sulfonamide
bond, urea bond, urethane bond or the like. Also, each of these
groups may be further substituted. Examples of the substituent
include a halogen atom, alkyl group, aryl group, heterocyclic
group, hydroxyl group, alkoxy group, aryloxy group, alkylthio
group, arylthio group, acyloxy group, alkoxycarbonyl group,
carbamoyloxy group, acyl group, acyloxy group, acylamino group,
sulfonamide group, carbamoyl group, sulfamoyl group, sulfonyl
group, phosphoryl group, carboxyl group and sulfo group. Among
these groups, a halogen atom, alkyl group, hydroxy group, alkoxy
group, aryloxy group and acyloxy group are preferable.
[0101] Specific examples of the vinylsulfone-series hardener
include, though not limited to, the following compounds (VS-1) to
(VS-27). ##STR1## ##STR2##
[0102] These hardeners may be obtained with reference to the method
described in, for example, the specification of U.S. Pat. No.
4,173,481.
[0103] Furthermore, as the chlorotriazine-series hardener, a
1,3,5-triazine compound in which at least one of the 2-position,
4-position and 6-position of the triazine ring in the compound is
substituted with a chlorine atom, is preferable. A 1,3,5-triazine
compound in which two or three of the 2-position, 4-position and
6-position of the triazine ring each are substituted with a
chlorine atom, is more preferable. Alternatively, use may be made
of a 1,3,5-triazine compound in which at least one of the
2-position, 4-position and 6-position of the triazine ring is
substituted with a chlorine atom, and the remainder position(s)
is/are substituted with a group(s) or atom(s) other than a chlorine
atom. Examples of these other groups include a hydrogen atom,
bromine atom, fluorine atom, iodine atom, alkyl group, alkenyl
group, alkynyl group, cycloalkyl group, cycloalkenyl group, aryl
group, heterocyclic group, hydroxy group, nitro group, cyano group,
amino group, hydroxylamino group, alkylamino group, arylamino
group, heterocyclic amino group, acylamino group, sulfonamide
group, carbamoyl group, sulfamoyl group, sulfo group, carboxyl
group, alkoxy group, alkenoxy group, aryloxy group, heterocyclic
oxy group, acyl group, acyloxy group, alkyl- or aryl-sulfonyl
group, alkyl- or aryl-sulfinyl group, alkyl- or aryl-sulfonyloxy
group, mercapto group, alkylthio group, alkenylthio group, arylthio
group, heterocyclic thio group and alkyloxy- or aryloxy-carbonyl
group.
[0104] Specific examples of the chlorotriazine-series hardener
include, though not limited to,
4,6-dichloro-2-hydroxy-1,3,5-triazine or its Na salt,
2-chloro-4,6-diphenoxytriazine,
2-chloro-4,6-bis[2,4,6-trimethylphenoxy]triazine,
2-chloro-4,6-diglycidoxy-1,3,5-triazine,
2-chloro-4-(n-butoxy)-6-glycidoxy-1,3,5-triazine,
2-chloro-4-(2,4,6-trimethylphenoxy)-6-glycidoxy-1,3,5-triazine,
2-chloro-4-(2-chloroethoxy)-6-(2,4,6-trimethylphenoxy)-1,3,5-triazine,
2-chloro-4-(2-bromoethoxy)-6-(2,4,6-trimethylphenoxy)-1,3,5-triazine,
2-chloro-4-(2-di-n-butylphosphateethoxy)-6-(2,4,6-trimethylphenoxy)-1,3,5-
-triazine and
2-chloro-4-(2-di-n-butylphosphateethoxy)-6-(2,6-xylenoxy)-1,3,5-triazine.
[0105] Such a compound is easily produced by reacting cyanur
chloride (namely, 2,4,6-trichlorotriazine) with, for example, a
hydroxy compound, thio compound or amino compound corresponding to
the substituent on the heterocycle.
[0106] These hardeners are preferably used in an amount of 0.001 to
1 g, and further preferably 0.005 to 0.5 g, per 1 g of the
water-soluble polymer.
<Emulsion>
[0107] An emulsion is preferably incorporated in the receptor layer
of the heat-sensitive transfer image-receiving sheet of the present
invention. The following is a detailed explanation of the emulsion
that is preferably used in the present invention.
[0108] Hydrophobic additives, such as a lubricant, an antioxidant,
and the like, can be introduced into a layer of the image-receiving
sheet (e.g. the receptor layer, the heat insulation layer, the
undercoat layer), by using a known method described in U.S. Pat.
No. 2,322,027, or the like. In this case, a high-boiling organic
solvent, as described in U.S. Pat. No. 4,555,470, U.S. Pat. No.
4,536,466, U.S. Pat. No. 4,536,467, U.S. Pat. No. 4,587,206, U.S.
Pat. No. 4,555,476 and U.S. Pat. No. 4,599,296, JP-B-3-62256, and
the like, may be used singly or in combination with a low-boiling
organic solvent having a boiling point of 50 to 160.degree. C.,
according to the need. Also, these lubricants, antioxidants, and
high-boiling organic solvents may be respectively used in
combination of two or more.
[0109] As the antioxidant (hereinafter, also referred to as a
radical trapper in this specification), a compound represented by
any one of the following formulae (E-1) to (E-3) is preferably
used. ##STR3##
[0110] R.sub.41 represents an aliphatic group, an aryl group, a
heterocyclic group, an acyl group, an aliphatic oxycarbonyl group,
an aryloxycarbonyl group, an aliphatic sulfonyl group, an
arylsulfonyl group, a phosphoryl group, or a group
--Si(R.sub.47)(R.sub.48)(R.sub.49) in which R.sub.47, R.sub.48 and
R.sub.49 each independently represent an aliphatic group, an aryl
group, an aliphatic oxy group, or an aryloxy group. R.sub.42 to
R.sub.46 each independently represent a hydrogen atom, or a
substituent. Examples of the substituent include a halogen atom,
aliphatic group (including an alkyl group, alkenyl group, alkynyl
group, cycloalkyl group, and cycloalkenyl group), aryl group,
heterocyclic group, hydroxy group, mercapto group, aliphaticoxy
group, aryloxy group, heterocyclic oxy group, aliphaticthio group,
arylthio group, heterocyclic thio group, amino group,
aliphaticamino group, arylamino group, heterocyclic amino group,
acylamino group, sulfonamide group, cyano group, nitro group,
carbamoyl group, sulfamoyl group, acyl group, aliphatic oxycarbonyl
group, and aryloxycarbonyl group. R.sub.a1, R.sub.a2, R.sub.a3, and
R.sub.a4 each independently represent a hydrogen atom, or an
aliphatic group (for example, methyl, ethyl).
[0111] With respect to the compounds represented by any one of the
Formulae (E-1) to (E-3), the groups that are preferred from the
viewpoint of the effect to be obtained by the present invention,
are explained below.
[0112] In the Formulae (E-1) to (E-3), it is preferred that
R.sub.41 represents an aliphatic group, an acyl group, an aliphatic
oxycarbonyl group, an aryloxycarbonyl group, or a phosphoryl group,
and R.sub.42, R.sub.43, R.sub.45, and R.sub.46 each independently
represent a hydrogen atom, an aliphatic group, an aliphatic oxy
group, or an acylamino group. It is more preferred that R.sub.41
represents an aliphatic group, and R.sub.42, R.sub.43, R.sub.45 and
R.sub.46 each independently represent a hydrogen atom or an
aliphatic group.
[0113] Preferable specific examples of the compounds represented by
any one of the Formulae (E-1) to (E-3) are shown below, but the
present invention is not limited to these compounds. ##STR4##
##STR5##
[0114] A content of the antioxidizing agent is preferably from 1.0
to 7.0 mass %, more preferably from 2.5 to 5.0 mass %, based on a
solid content in the latex polymer.
[0115] As the lubricant, solid waxes such as polyethylene wax,
amide wax and Teflon (registered trademark) powder; silicone oil,
phosphate-series compounds, fluorine-based surfactants,
silicone-based surfactants and others including releasing agents
known in the technical fields concerned may be used.
Fluorine-series compounds typified by fluorine-based surfactants,
silicone-based surfactants and silicone-series compounds such as
silicone oil and/or its hardened products are preferably used. A
content of the lubricant is preferably from 1.0 to 10.0 mass %,
more preferably from 1.5 to 2.5 mass %, based on a solid content in
the latex polymer.
[0116] As the silicone oil as the lubricant, straight silicone oil
and modified silicone oil or their hardened products may be
used.
[0117] Examples of the straight silicone oil include
dimethylsilicone oil, methylphenylsilicone oil and methyl hydrogen
silicone oil. Examples of the dimethylsilicone oil include KF96-10,
KF96-100, KF96-1000, KF96H-10000, KF96H-12500 and KF96H-100000 (all
of these names are trade names, manufactured by Shin-Etsu Chemical
Co., Ltd.). Examples of the methylphenylsilicone oil include
KF50-100, KF54 and KF56 (all of these names are trade names,
manufactured by Shin-Etsu Chemical Co., Ltd.).
[0118] The modified silicone oil may be classified into reactive
silicone oils and non-reactive silicone oils. Examples of the
reactive silicone oils include amino-modified, epoxy-modified,
carboxyl-modified, hydroxy-modified, methacryl-modified,
mercapto-modified, phenol-modified or one-terminal
reactive/hetero-functional group-modified silicone oils. Examples
of the amino-modified silicone oil include KF-393, KF-857, KF-858,
X-22-3680, X-22-3801C, KF-8010, X-22-161A and KF-8012 (all of these
names are trade names, manufactured by Shin-Etsu Chemical Co.,
Ltd.). Examples of the epoxy-modified silicone oil include KF-100T,
KF-101, KF-60-164, KF-103, X-22-343 and X-22-3000T (all of these
names are trade names, manufactured by Shin-Etsu Chemical Co.,
Ltd.). Examples of the carboxyl-modified silicone oil include
X-22-162C (trade name, manufactured by Shin-Etsu Chemical Co.,
Ltd.). Examples of the hydroxy-modified silicone oil include
X-22-160AS, KF-6001, KF-6002, KF-6003, X-22-170DX, X-22-176DX,
X-22-176D and X-22-176DF (all of these names are trade names,
manufactured by Shin-Etsu Chemical Co., Ltd.). Examples of the
methacryl-modified silicone oil include X-22-164A, X-22-164C,
X-24-8201, X-22-174D and X-22-2426 (all of these names are trade
names, manufactured by Shin-Etsu Chemical Co., Ltd.).
[0119] Reactive silicone oils may be hardened upon use, and may be
classified into a reaction-curable type, photocurable type,
catalyst-curable type, and the like. Among these types, silicone
oil that is the reaction-curable type is particularly preferable.
As the reaction-curable type silicone oil, products obtained by
reacting an amino-modified silicone oil with an epoxy-modified
silicone oil and then by curing are preferable. Also, examples of
the catalyst-curable type or photocurable type silicone oil include
KS-705F-PS, KS-705F-PS-1 and KS-770-PL-3 (all of these names are
trade names, catalyst-curable silicone oils, manufactured by
Shin-Etsu Chemical Co., Ltd.) and KS-720 and KS-774-PL-3 (all of
these names are trade names, photocurable silicone oils,
manufactured by Shin-Etsu Chemical Co., Ltd.). The addition amount
of the curable type silicone oil is preferably 0.5 to 30% by mass
based on the resin constituting the receptor layer. The releasing
agent is used preferably in an amount of 2 to 4% by mass and
further preferably 2 to 3% by mass based on 100 parts by mass of
the polyester resin. If the amount is too small, the releasability
cannot be secured without fail, whereas if the amount is excessive,
a protective layer is not transferred to the image-receiving sheet
resultantly.
[0120] Examples of the non-reactive silicone oil include
polyether-modified, methylstyryl-modified, alkyl-modified, higher
fatty acid ester-modified, hydrophilic special-modified, higher
alkoxy-modified or fluorine-modified silicone oils. Examples of the
polyether-modified silicone oil include KF-6012 (trade name,
manufactured by Shin-Etsu Chemical Co., Ltd.) and examples of the
methylstyryl-modified silicone oil include 24-510 and KF41-410 (all
of these names are trade names, manufactured by Shin-Etsu Chemical
Co., Ltd.). Modified silicones represented by any one of the
following Formulae 1 to 3 may also be used. ##STR6##
[0121] In the Formula 1, R represents a hydrogen atom or a
straight-chain or branched alkyl group which may be substituted
with an aryl or cycloalkyl group. m and n respectively denote an
integer of 2,000 or less, and a and b respectively denote an
integer of 30 or less. ##STR7##
[0122] In the Formula 2, R represents a hydrogen atom or a
straight-chain or branched alkyl group which may be substituted
with an aryl or cycloalkyl group. m denotes an integer of 2,000 or
less, and a and b respectively denote an integer of 30 or less.
##STR8##
[0123] In the Formula 3, R represents a hydrogen atom or a
straight-chain or branched alkyl group which may be substituted
with an aryl or cycloalkyl group. m and n respectively denote an
integer of 2,000 or less, and a and b respectively denote an
integer of 30 or less. R.sup.1 represents a single bond or a
divalent linking group, E represents an ethylene group which may be
further substituted, and P represents a propylene group which may
be further substituted.
[0124] Silicone oils such as those mentioned above are described in
"SILICONE HANDBOOK" (The Nikkan Kogyo Shimbun, Ltd.) and the
technologies described in each publication of JP-A-8-108636 and
JP-A-2002-264543 may be preferably used as the technologies to cure
the curable type silicone oils.
[0125] Examples of the high-boiling organic solvent include
phthalates (e.g., dibutyl phthalate, dioctyl phthalate,
di-2-ethylhexyl phthalate), phosphates or phosphonates (e.g.,
triphenyl phosphate, tricresyl phosphate, tri-2-ethylhexyl
phosphate), fatty acid esters (e.g., di-2-ethylhexyl succinate,
tributyl citrate), benzoates (e.g., 2-ethylhexyl benzoate, dodecyl
benzoate), amides (e.g., N,N-diethyldodecane amide,
N,N-dimethylolein amide), alcohols or phenols (e.g., iso-stearyl
alcohol, 2,4-di-tert-amyl phenol), anilines (e.g.,
N,N-dibutyl-2-butoxy-5-tert-octylaniline), chlorinated paraffins,
hydrocarbons (e.g., dodecyl benzene, diisopropyl naphthalene), and
carboxylic acids (e.g., 2-(2,4-di-tert-amyl phenoxy)butyrate).
[0126] Preferably the compounds shown below are used. ##STR9##
[0127] Further, the high-boiling organic solvent may be used in
combination with, as an auxiliary solvent, an organic solvent
having a boiling point of 30.degree. C. or more and 160.degree. C.
or less, such as ethyl acetate, butyl acetate, methyl ethyl ketone,
cyclohexanone, methylcellosolve acetate, or the like. The
high-boiling organic solvent is used in an amount of generally 1 to
10 g, preferably 5 g or less, and more preferably 1 to 0.1 g, per 1
g of the hydrophobic additives to be used. The amount is also
preferably 1 ml or less, more preferably 0.5 ml or less, and
particularly preferably 0.3 ml or less, per 1 g of the binder.
[0128] A dispersion method that uses a polymer, as described in
JP-B-51-39853 and JP-A-51-59943, and a method wherein the addition
is made with them in the form of a dispersion of fine particles, as
described in, for example, JP-A-62-30242, can also be used. In the
case of a compound that is substantially insoluble in water, other
than the above methods, a method can be used wherein the compound
is dispersed and contained in the form of fine particles in a
binder.
[0129] When the hydrophobic compound is dispersed in a hydrophilic
colloid, various surfactants may be used. For example, those listed
as examples of the surfactant in JP-A-59-157636, page (37) to page
(38) may be used. It is also possible to use phosphates-based
surfactants described in JP-A-7-56267, JP-A-7-228589, and West
German Patent Application Laid-Open (OLS) No. 1,932,299A.
<Ultraviolet Absorber>
[0130] Also, in the present invention, in order to improve light
resistance, an ultraviolet absorber may be added to the receptor
layer. In this case, when this ultraviolet absorber is made to have
a higher molecular weight, it can be secured to the receptor layer
so that it can be prevented, for instance, from being diffused into
the ink sheet and from being sublimated and vaporized by
heating.
[0131] As the ultraviolet absorber, compounds having various
ultraviolet absorber skeletons, which are widely used in the field
of information recording, may be used. Specific examples of the
ultraviolet absorber may include compounds having a
2-hydroxybenzotriazole type ultraviolet absorber skeleton,
2-hydroxybenzotriazine type ultraviolet absorber skeleton, or
2-hydroxybenzophenon type ultraviolet absorber skeleton. Compounds
having a benzotriazole-type or triazine-type skeleton are
preferable from the viewpoint of ultraviolet absorbing ability
(absorption coefficient) and stability, and compounds having a
benzotriazole-type or benzophenone-type skeleton are preferable
from the viewpoint of obtaining a higher-molecular weight and using
in a form of a latex. Specifically, ultraviolet absorbers described
in, for example, JP-A-2004-361936 may be used.
[0132] The ultraviolet absorber preferably absorbs light at
wavelengths in the ultraviolet region, and the absorption edge of
the absorption of the ultraviolet absorber is preferably out of the
visible region. Specifically, when it is added to the receptor
layer to form a heat-sensitive transfer image-receiving sheet, the
heat-sensitive transfer image-receiving sheet has a reflection
density of, preferably, Abs 0.5 or more at 370 nm, and more
preferably Abs 0.5 or more at 380 nm. Also, the heat-sensitive
transfer image-receiving sheet has a reflection density of,
preferably, Abs 0.1 or less at 400 nm. If the reflection density at
a wavelength range exceeding 400 nm is high, it is not preferable
because an image is made yellowish.
[0133] In the present invention, the ultraviolet absorber is
preferably made to have a higher molecular weight. The ultraviolet
absorber has a mass average molecular weight of preferably 10,000
or more, and more preferably 100,000 or more. As a means of
obtaining a higher-molecular weight ultraviolet absorber, it is
preferable to graft an ultraviolet absorber on a polymer. The
polymer as the principal chain preferably has a polymer skeleton
less capable of being dyed than the receptor polymer to be used
together. Also, when the polymer is used to form a film, the film
preferably has sufficient film strength. The graft ratio of the
ultraviolet absorber to the polymer principal chain is preferably 5
to 20% by mass and more preferably 8 to 15% by mass.
[0134] Also, it is more preferable that the
ultraviolet-absorber-grafted polymer is made to be used in a form
of a latex. When the polymer is made to be used in a form of a
latex, an aqueous dispersion-system coating solution may be used in
application and coating to form the receptor layer, and this
enables reduction of production cost. As a method of making the
latex polymer (or making the polymer latex-wise), a method
described in, for example, Japanese Patent No. 3450339 may be used.
As the ultraviolet absorber to be used in a form of a latex, the
following commercially available ultraviolet absorbers may be used
which include ULS-700, ULS-1700, ULS-1383MA, ULS-1635 MH, XL-7016,
ULS-933LP, and ULS-935LH, manufactured by Ipposha Oil Industries
Co., Ltd.; and New Coat UVA-1025W, New Coat UVA-204W, and New Coat
UVA-4512M, manufactured by Shin-Nakamura Chemical Co., Ltd. (all of
these names are trade names).
[0135] In the case of using an ultraviolet-absorber-grafted polymer
in a form of a latex, it may be mixed with a latex of the receptor
polymer capable of being dyed, and the resulting mixture is coated.
By doing so, a receptor layer, in which the ultraviolet absorber is
homogeneously dispersed, can be formed.
[0136] The addition amount of the ultraviolet-absorber-grafted
polymer or its latex is preferably 5 to 50 parts by mass, and more
preferably 10 to 30 parts by mass, to 100 parts by mass of the
receptor latex polymer capable of being dyed to be used to form the
receptor layer.
<Releasing Agent>
[0137] Also, a releasing agent may be compounded in the receptor
layer, in order to prevent thermal fusion with the heat-sensitive
transfer sheet when an image is formed. As the releasing agent, a
silicone oil, a phosphate-based plasticizer, a fluorine-series
compound, or various wax dispersions may be used, and the silicone
oil and the wax dispersions are particularly preferably used.
[0138] As the silicone oil, modified silicone oil, such as
epoxy-modified, alkyl-modified, amino-modified, carboxyl-modified,
alcohol-modified, fluorine-modified, alkyl aralkyl
polyether-modified, epoxy/polyether-modified, or polyether-modified
silicone oil, is preferably used. Among these, a reaction product
between vinyl-modified silicone oil and hydrogen-modified silicone
oil is preferable. The amount of the releasing agent is preferably
0.2 to 30 parts by mass, per 100 parts by mass of the receptor
polymer.
[0139] As the wax dispersions, known dispersions may be used. In
the present invention, "wax" means an organic compound having an
alkyl chain which is in a solid or semisolid state at room
temperature (according to the definition given in Kaitei Wax no
Seishitsu to Oyo (Revised edition, Properties and Applications of
Wax), Saiwai Shobo (1989)). Preferable examples of the organic
compound include candelilla wax, carnauba wax, rice wax, haze wax,
montan wax, ozokerite, paraffin wax, microcrystalline wax,
petrolatum, Fischer-Tropsch wax, polyethylene wax, montan wax
derivatives, paraffin wax derivatives, microcrystalline wax
derivatives, hydrogenated ricinus, hydrogenated ricinus
derivatives, 12-hydroxystearic acid, stearic acid amide, phthalic
anhydride imide, chlorinated hydrocarbons, and other mixed waxes.
Of these waxes, carnauba wax, montan wax and derivatives thereof,
paraffin wax and derivatives thereof, microcrystalline wax and
derivatives thereof, polyethylene wax and stearic acid amide are
preferred; carnauba wax, montan wax and derivatives thereof,
microcrystalline wax and stearic acid amide are more preferred; and
montan wax, montan wax derivatives and microcrystalline wax are
further preferred.
[0140] These waxes are selected from waxes having melting points of
generally 25.degree. C. to 120.degree. C., preferably 40.degree. C.
to 100.degree. C., more preferably 60.degree. C. to 90.degree.
C.
[0141] The wax is preferably in a state of being dispersed in
water, more preferably in the form of fine particles. Dispersing
waxes in water and forming waxes into fine particles can be
performed using the methods as described in "Kaitei Wax no
Seishitsu to Oyo (Revised version, Properties and Applications of
Wax)", Saiwai Shobo (1989).
[0142] The addition amount of wax is preferably from 0.5 to 30% by
mass, more preferably from 1 to 20% by mass, and further preferably
from 1.5 to 15% by mass, of the amount of total solid content in
the receptor layer.
[0143] The amount of the receptor layer to be applied is preferably
0.5 to 10 g/m.sup.2 (solid basis, hereinafter, the amount to be
applied in the present specification means a value on solid basis
unless otherwise noted), more preferably 1 to 8 g/m.sup.2, and
further preferably 2 to 7 g/m.sup.2. The film thickness of the
receptor layer is preferably 1 to 20 .mu.m.
(Heat Insulation Layer)
[0144] A heat insulation layer serves to protect the support from
heat when a thermal head or the like is used to carry out a
transfer operation under heating. Also, because the heat insulation
layer has high cushion properties, a heat-sensitive transfer
image-receiving sheet having high printing sensitivity can be
obtained even in the case of using paper as a substrate (support).
The heat insulation layer may be a single layer, or multi-layers.
The heat insulation layer is generally arranged at a nearer
location to the support than the receptor layer.
[0145] In the image-receiving sheet of the present invention, the
heat insulation layer contains hollow polymer particles.
[0146] The hollow polymer particles in the present invention are
polymer particles having independent pores inside of the particles.
Examples of the hollow polymer particles include (1) non-foaming
type hollow particles obtained in the following manner: a
dispersion medium such as water is contained inside of a capsule
wall formed of a polystyrene, acryl resin, or styrene/acryl resin
and, after a coating solution is applied and dried, the dispersion
medium in the particles is vaporized out of the particles, with the
result that the inside of each particle forms a hollow; (2) foaming
type microballoons obtained in the following manner: a low-boiling
point liquid such as butane and pentane is encapsulated in a resin
constituted of any one of polyvinylidene chloride,
polyacrylonitrile, polyacrylic acid and polyacrylate, and their
mixture or polymer, and after the resin coating material is
applied, it is heated to expand the low-boiling point liquid inside
of the particles whereby the inside of each particle is made to be
hollow; and (3) microballoons obtained by foaming the above (2)
under heating in advance, to make hollow polymer particles.
[0147] Among these, the non-foaming type hollow particles according
to (1) are preferable. In the case of the microballoons according
to (2), it is difficult to form a smooth surface. This is because
it is necessary to foam microballoons by heating or the like
method, after forming a heat insulation layer by coating. In the
case of (3), since the microballoons foamed in advance by heating
contain a gas therein, it is difficult to prepare a uniform coating
solution thereof in producing an image-receiving sheet by coating,
and thus also difficult to form a smooth surface.
[0148] The method of producing the non-foaming type hollow
particles of (1) is not particularly limited, and examples thereof
include those described in JP-A-56-32513, JP-A-63-213509,
JP-A-64-1704, JP-A-3-26724, JP-A-5-279409, JP-A-6-248012, and
JP-A-10-182761.
[0149] The average particle diameter (particle size) of the hollow
polymer particles is 0.3 to 1.0 Kim. If the particle size is too
small, the resultant particles tend to have a smaller hollow ratio,
which may cause it impossible to obtain a desired heat-insulation
property; whereas, if the particle size is too large, frequencies
of surface defects generated due to causes other than the bulky
particles in the heat insulation layer can increase.
[0150] In the present invention, the size of a hollow polymer
particle is calculated as a circle-equivalent diameter based on a
measurement of the outer periphery of a particle observed under a
transmission electron microscope. Herein the term
"circle-equivalent diameter" refers to the diameter of a circle
having an area equivalent to the projected area of an individual
particle. The average particle diameter is determined by observing
at least 300 hollow polymer particles under a transmission electron
microscope, to calculate the circle-equivalent diameters based on
the outer periphery of the particles, and obtaining an average
thereof.
[0151] Depending on conditions at preparation, the hollow polymer
particles can be mixed (contaminated) with some unplanned particles
having no hollow structure; in the present invention, the polymer
particles not in the hollow structure are not counted when
measuring the particle diameter. The particle not in the hollow
structure, which does not have a void therein, is lower in
heat-insulating property and often has a particle diameter-smaller
than that of the other particle in the hollow structure, rarely
affecting the properties of the heat insulation layer.
[0152] Bulky particles mixed in the hollow polymer particles are
not counted in calculation of the average particle diameter in the
present invention.
[0153] The number of the bulky particles having a particle diameter
of 10 .mu.m or more that may be contained in the hollow polymer
particles in the present invention is less than 1/5,000 with
respect to the total number of the hollow polymer particles. The
presence of bulky particles in the hollow particles at a ratio
higher than the above leads to increased frequency of the surface
defect.
[0154] The number of the bulky particles contained in the hollow
polymer particles, the ratio of total number of the hollow polymer
particles, and the size of the bulky particles are determined by
using a flow particle image analyzer FPIA-2100 (manufactured by
Sysmex Corp.). The measurement is performed in the LPF mode after a
dispersion of hollow polymer particles is diluted properly. The
dilution rate is determined according to the specification of the
device, but the concentration is preferably adjusted so that the
total number of the particles measured is in the range of 10,000 to
20000. The ratio of the bulky particles of 10 .mu.m or more in
diameter contained in the hollow polymer particles is determined
from the ratio of the number of bulky particles of 10 .mu.m or more
in diameter and the total number of the particles measured in the
measurement.
[0155] In measurement of the ratio of the bulky particles of 10
.mu.m or more contained in the hollow polymer particles in a sample
of a heat insulation layer formed by a method such as coating, the
binder in the sample is decomposed or dissolved by a suitable
method (for example, when gelatin is used as the binder, gelatin is
decomposed with a solution containing an enzyme, and when
polyvinylalcohol is used as the binder, it is dissolved with hot
water), to give a dispersion of the hollow polymer particles, and
the dispersion is analyzed.
[0156] Such a hollow polymer particles from which the bulky
particles of 10 .mu.m or more in diameter are removed may be
prepared by any method. For example, in the case of a hollow
polymer particles containing bulky particles of 10 .mu.m or more in
diameter in an amount of 1/1,200 with respect to the total number
of particles, it is possible to reduce the number of bulky
particles to less than 1/5,000 of the total particle number by
filtering the dispersion four times through a filtration filter
having a rated filtration accuracy of about 10 .mu.m. Although some
caution should be given to the material and the shape of the filter
for use then and the filtration conditions, but they are not
particularly limited as long as bulky particles can be removed.
Alternatively other than filtration, any method that separates
particles according to size, such as centrifugation, may be
used.
[0157] As mentioned above, in the present invention, it is
preferred that these hollow polymer particles are prepared by
removing the bulky particles using the filtration method with a
filter or the centrifugation method.
[0158] These hollow polymer particles preferably have a hollow
ratio of about 20 to 70%, more preferably 20 to 60%. With a too
small hollow ratio, it cannot give a sufficient heat-insulating
efficiency; while with an excessively large hollow ratio for the
hollow particles that have the above-described preferable particle
diameter, imperfect hollow particles increase, with prohibiting
sufficient film strength.
[0159] The hollow ratio (%) of hollow polymer particles in the
present invention is determined by taking a transmission electron
microscope photograph of at least 300 hollow polymer particles,
measuring the circle-equivalent diameter of the void (hollow) in
each particle and the diameter of the hollow polymer particle,
calculating individual hollow ratio (%) from the measured values
according to the following formula, and averaging the individual
hollow ratios: Individual hollow ratio(%)=(Circle-equivalent
diameter of void).sup.3/(Diameter of hollow polymer
particle).sup.3.times.100
[0160] The glass transition temperature (Tg) of the hollow polymer
particles is preferably 70.degree. C. or more and more preferably
100.degree. C. or more. These hollow polymer particles may be used
in combinations of two or more.
[0161] A commercial product may also be used as the hollow polymer
particles, if a proper removal of the bulky particles is carried
out. Specifically, Lowpake 1055 manufactured by Rohm and Haas Japan
KK, SX866(B) manufactured by JSR Co., Ltd., Nippol MH 5055
manufactured by Zeon Corporation (all of the names are trade names)
and the like may be used after subjecting to, for example, the
filtration treatment described above.
[0162] A water-dispersible resin or water-soluble type resin is
preferably contained, as a binder, in the heat insulation layer
containing the hollow polymer particles. As the binder resin that
can be used in the present invention, known resins such as an acryl
resin, styrene/acryl copolymer, polystyrene resin, polyvinyl
alcohol resin, vinyl acetate resin, ethylene/vinyl acetate
copolymer, vinyl chloride/vinyl acetate copolymer,
styrene/butadiene copolymer, polyvinylidene chloride resin,
cellulose derivative, casein, starch, and gelatin may be used.
Also, these resins may be used either singly or as mixtures.
[0163] The solid content of the hollow polymer particles in the
heat insulation layer is preferably 60% by mass or more, and more
preferably 65% by mass or more, based on the total solid content of
the heat insulation layer. Also, the ratio by mass of the solid
content of the hollow polymer particles in the coating solution is
preferably 1 to 70% by mass and more preferably 10 to 40% by mass.
If the ratio of the hollow polymer particles is excessively low,
sufficient heat insulation cannot be obtained, whereas if the ratio
of the hollow polymer particles is excessively large, the adhesion
between the hollow polymer particles is reduced, and thereby
sufficient film strength cannot be obtained, causing deterioration
in abrasion resistance.
[0164] The heat insulation layer of the heat-sensitive transfer
image-receiving sheet of the present invention is preferably free
of any resins that are not resistant to an organic solvent, except
for the hollow polymer particles. Incorporation of the resin that
is not resistant to an organic solvent (resin having a dye-dyeing
affinity) in the heat insulation layer is not preferable in view of
increase in loss of image definition after image transfer. It is
assumed that the color-edge definition loss increases by the reason
that owing to the presence of both the resin having a dye-dyeing
affinity and the hollow polymer particles in the heat insulation
layer, a transferred dye that has dyed the receptor layer migrates
through the heat insulation layer adjacent thereto with the lapse
of time.
[0165] Herein, the term "the resin that is not resistant to an
organic solvent" means a resin having solubility in an organic
solvent (e.g., methyl ethyl ketone, ethyl acetate, benzene,
toluene, xylene) of 1 mass % or more, preferably 0.5 mass % or
more. For example, the above-mentioned latex polymer is included in
the category of "the resin that is not resistant to an organic
solvent".
[0166] The heat insulation layer preferably contains the
above-mentioned water-soluble polymer. Preferable compounds of the
water-soluble polymer are gelatin, polyvinyl alcohol, and the
like.
[0167] An amount of the water-soluble polymer to be added in the
heat insulation layer is preferably from 1 to 75 mass %, more
preferably from 1 to 50 mass % to the entire heat insulation
layer.
[0168] The heat insulation layer of the present invention is
preferable formed by applying an aqueous type (water-based) coating
solution. The coating amount of the above hollow polymer particles
in the heat insulation layer is preferably 1 to 100 g/m.sup.2 (i.e.
g per area (m.sup.2) of the heat-sensitive transfer image-receiving
sheet), and more preferably 5 to 20 g/m.sup.2 (i.e. g per area
(m.sup.2) of the heat-sensitive transfer image-receiving
sheet).
[0169] A part or all of the water-soluble polymer that is contained
in the heat insulation layer has been preferably cross-linked with
the crosslinking agent. Preferable compounds as well as a
preferable amount of the crosslinking agent to be used are the same
as mentioned above.
[0170] A preferred ratio of a cross-linked water-soluble polymer in
the heat insulation layer varies depending on the kind of the
crosslinking agent, but the water-soluble polymer in the heat
insulation layer is crosslinked by preferably 0.1 to 20 mass %,
more preferably 1 to 10 mass %, based on the entire water-soluble
polymer.
[0171] A thickness of the heat insulation layer containing the
hollow polymer particles is preferably from 5 to 50 .mu.m, more
preferably from 5 to 40 .mu.m.
[0172] A void ratio (porosity ratio) of the heat insulation layer,
which is calculated from the thickness of the heat insulation layer
containing hollow polymer particles and the solid-matter coating
amount of the heat insulation layer including the hollow polymer
particles, is preferably 10 to 70% and more preferably 15 to 60%.
When the void ratio is too low, sufficient heat insulation property
cannot be obtained. When the void ratio is too large, the binding
force among hollow polymer particles deteriorates, and thus
sufficient film strength cannot be obtained, and abrasion
resistance deteriorates.
[0173] The void ratio of the heat insulation layer as referred to
herein is a value V calculated according to the Formula (b) below.
V=1-L/L.times..SIGMA.gidi Formula (b)
[0174] In Formula (b), L represents the thickness of the
heat-insulating layer; gi represents the coating amount of a
particular material i in terms of solid matter for the
heat-insulating layer; and di represents the specific density of
the particular material i. When di represents the specific density
of the hollow polymer particles, di is the specific density of the
wall material of hollow polymer particles.
(Undercoat Layer)
[0175] An undercoat layer may be formed between the receptor layer
and the heat insulation layer. As the undercoat layer, for example,
at least one of a white background controlling layer, a charge
controlling layer, an adhesive layer, and a primer layer is formed.
These layers may be formed in the same manner as those described
in, for example, each specification of Japanese Patent Nos. 3585599
and 2925244.
(Support)
[0176] In the present invention, a waterproof support is preferably
used as the support. The use of the waterproof-support makes it
possible to prevent the support from absorbing moisture, whereby a
fluctuation in the performance of the receptor layer with time can
be prevented. As the waterproof support, for example, coated paper
or laminate paper may be used.
--Coated Paper--
[0177] The coated paper is paper obtained by coating a sheet such
as base paper with various resins, rubber latexes, or
high-molecular materials, on one side or both sides of the sheet,
wherein the coating amount differs depending on its use. Examples
of such coated paper include art paper, cast coated paper, and
Yankee paper.
[0178] It is proper to use a thermoplastic resin as the resin to be
applied to the surface(s) of the base paper and the like. As such a
thermoplastic resin, the following thermoplastic resins (A) to (H)
may be exemplified.
(A) Polyolefin resins such as polyethylene resin and polypropylene
resin; copolymer resins composed of an olefin such as ethylene or
propylene and another vinyl monomer; and acrylic resins.
[0179] (B) Thermoplastic resins having an ester linkage: for
example, polyester resins obtained by condensation of a
dicarboxylic acid component (such a dicarboxylic acid component may
be substituted with a sulfonic acid group, a carboxyl group, or the
like) and an alcohol component (such an alcohol component may be
substituted with a hydroxyl group, or the like); polyacrylate
resins or polymethacrylate resins such as polymethylmethacrylate,
polybutylmethacrylate, polymethylacrylate, polybutylacrylate, or
the like; polycarbonate resins, polyvinyl acetate resins, styrene
acrylate resins, styrene-methacrylate copolymer resins,
vinyltoluene acrylate resins, or the like.
[0180] Concrete examples of them are those described in
JP-A-59-101395, JP-A-63-7971, JP-A-63-7972, JP-A-63-7973, and
JP-A-60-294862.
[0181] Commercially available thermoplastic resins usable herein
are, for example, Vylon 290, Vylon 200, Vylon 280, Vylon 300, Vylon
103, Vylon GK-140, and Vylon GK-130 (products of Toyobo Co., Ltd.);
Tafton NE-382, Tafton U-5, ATR-2009, and ATR-2010 (products of Kao
Corporation); Elitel UE 3500, UE 3210, XA-8153, KZA-7049, and
KZA-1449 (products of Unitika Ltd.); and Polyester TP-220 and R-188
(products of The Nippon Synthetic Chemical Industry Co., Ltd.); and
thermoplastic resins in the Hyros series from Seiko Chemical
Industries Co., Ltd., and the like (all of these names are trade
names).
(C) Polyurethane resins, etc.
(D) Polyamide resins, urea resins, etc.
(E) Polysulfone resins, etc.
(F) Polyvinyl chloride resins, polyvinylidene chloride resins,
vinyl chloride/vinyl acetate copolymer resins, vinyl chloride/vinyl
propionate copolymer resins, etc.
(G) Polyol resins such as polyvinyl butyral; and cellulose resins
such as ethyl cellulose resin and cellulose acetate resin.
(H) Polycaprolactone resins, styrene/maleic anhydride resins,
polyacrylonitrile resins, polyether resins, epoxy resins, and
phenolic resins.
[0182] The thermoplastic resins may be used either alone or in
combination of two or more.
[0183] The thermoplastic resin may contain a whitener, a conductive
agent, a filler, a pigment or dye including, for example, titanium
oxide, ultramarine blue, and carbon black; or the like, if
necessary.
--Laminated Paper--
[0184] The laminated paper is a paper which is formed by laminating
various kinds of resin, rubber, polymer sheets or films on a sheet
such as a base paper or the like. Specific examples of the
materials useable for the lamination include polyolefins, polyvinyl
chlorides, polyethylene terephthalates, polystyrenes,
polymethacrylates, polycarbonates, polyimides, and
triacetylcelluloses. These resins may be used alone, or in
combination of two or more.
[0185] Generally, the polyolefins are prepared by using a
low-density polyethylene. However, for improving the thermal
resistance of the support, it is preferred to use a polypropylene,
a blend of a polypropylene and a polyethylene, a high-density
polyethylene, or a blend of a high-density polyethylene and a
low-density polyethylene. From the viewpoint of cost and its
suitableness for the laminate, it is preferred to use the blend of
a high-density polyethylene and a low-density polyethylene.
[0186] The blend of a high-density polyethylene and a low-density
polyethylene is preferably used in a blend ratio (a mass ratio) of
1/9 to 9/1, more preferably 2/8 to 8/2, and most preferably 3/7 to
7/3. When the thermoplastic resin layer is formed on the both
surfaces of the support, the back side of the support is preferably
formed using, for example, the high-density polyethylene or the
blend of a high-density polyethylene and a low-density
polyethylene. The molecular weight of the polyethylenes is not
particularly limited. Preferably, both of the high-density
polyethylene and the low-density polyethylene have a melt index of
1.0 to 40 g/10 minute and a high extrudability.
[0187] The sheet or film may be subjected to a treatment to impart
white reflection thereto. As a method of such a treatment, for
example, a method of incorporating a pigment such as titanium oxide
into the sheet or film can be mentioned.
[0188] The support that can be used in the present invention
preferably has a base paper (base sheet) and a polyolefin resin
layer that is provided on both side or at least on the side of the
base paper to which the receptor layer is provided. The thickness
of the support is preferably from 25 .mu.m to 300 .mu.m, more
preferably from 50 .mu.m to 260 .mu.m, and further preferably from
75 .mu.m to 220 .mu.m. The support can have any rigidity according
to the purpose. When it is used as a support for
electrophotographic image-receiving sheet of photographic image
quality, the rigidity thereof is preferably near to that in a
support for use in color silver halide photography.
(Curling Control Layer)
[0189] When the support is exposed as it is, there is the case
where the heat-sensitive transfer image-receiving sheet is made to
curl by moisture and/or temperature in the environment. It is
therefore preferable to form a curling control layer on the
backside of the support. The curling control layer not only
prevents the image-receiving sheet from curling but also has a
water-proof function. For the curling control layer, a polyethylene
laminate, a polypropylene laminate or the like is used.
Specifically, the curling control layer may be formed in a manner
similar to those described in, for example, JP-A-61-110135 and
JP-A-6-202295.
(Writing Layer and Charge Controlling Layer)
[0190] For the writing layer and the charge control layer, an
inorganic oxide colloid, an ionic polymer, or the like may be used.
As the antistatic agent, any antistatic agents including cationic
antistatic agents such as a quaternary ammonium salt and polyamine
derivative, anionic antistatic agents such as alkyl phosphate, and
nonionic antistatic agents such as fatty acid ester may be used.
Specifically, the writing layer and the charge control layer may be
formed in a manner similar to those described in the specification
of Japanese Patent No. 3585585.
[0191] The method of producing the heat-sensitive transfer
image-receiving sheet for use in the present invention is explained
below.
[0192] The heat-sensitive transfer image-receiving sheet of the
present invention can be preferably formed, by applying at least
one receptor layer, an intermediate layer and at least one
heat-insulating layer, on a support, through simultaneous
multi-layer coating.
[0193] It is known that in the case of producing an image-receiving
sheet composed of plural layers having different functions from
each other (for example, an air cell layer, a heat insulation
layer, an intermediate layer, and a receptor layer) on a support,
it may be produced by applying and overlapping each layer one by
one, or by overlapping the layers each already coated on a support
or substrate, as shown in, for example, JP-A-2004-106283,
JP-A-2004-181888 and JP-A-2004-345267. It has been known in
photographic industries, on the other hand, that productivity can
be greatly improved, for example, by providing plural layers
through simultaneous multi-layer coating. For example, there are
known methods such as the so-called slide coating (slide coating
method) and curtain coating (curtain coating method) as described
in, for example, U.S. Pat. Nos. 2,761,791, 2,681,234, 3,508,947,
4,457,256 and 3,993,019; JP-A-63-54975, JP-A-61-278848,
JP-A-55-86557, JP-A-52-31727, JP-A-55-142565, JP-A-50-43140,
JP-A-63-80872, JP-A-54-54020, JP-A-5-104061, JP-A-5-127305, and
JP-B-49-7050; Edgar B. Gutoff, et al., "Coating and Drying Defects:
Troubleshooting Operating Problems", John Wiley & Sons Company,
1995, pp. 101-103; and "LIQUID FILM COATING", pp. 401 to 536
(Chapman & Hall, 1997).
[0194] In the present invention, it has been found that the
productivity is greatly improved and, at the same time, image
defects can be remarkably reduced, by using the above simultaneous
multilayer coating for the production of an image-receiving sheet
having a multilayer structure.
[0195] The plural layers in the present invention are structured
using resins as its major components. Coating solutions forming
each layer are preferably water-dispersible latexes. The solid
content by mass of the resin put in a latex state in each layer
coating solution is preferably in a range from 5 to 80% and
particularly preferably 20 to 60%. The average particle size of the
resin contained in the above water-dispersed latex is preferably 5
.mu.m or less and particularly preferably 1 .mu.m or less. The
above water-dispersed latex may contain a known additive, such as a
surfactant, a dispersant, and a binder resin, according to the
need.
[0196] In the present invention, it is preferred that a laminate
composed of plural layers be formed on a support and solidified
just after the forming, according to the method described in U.S.
Pat. No. 2,761,791. For example, in the case of solidifying a
multilayer structure by using a resin, it is preferable to raise
the temperature immediately after the plural layers are formed on
the support. Also, in the case where a binder (e.g., a gelatin) to
be gelled at lower temperatures is contained, there is the case
where it is preferable to drop the temperature immediately after
the plural layers are formed on the support.
[0197] In the present invention, the coating amount of a coating
solution per one layer constituting the multilayer is preferably in
a range from 1 g/m.sup.2 to 500 g/m.sup.2. The number of layers in
the multilayer structure may be arbitrarily selected from a number
of 2 or more. The receptor layer is preferably disposed as a layer
most apart from the support.
[0198] A heat-sensitive transfer sheet (ink sheet) used in
combination with the heat-sensitive transfer image-receiving sheet
according to the present invention as mentioned above at the time
of formation of heat transfer image is preferably a sheet having on
a support a dye layer containing a diffusion-transfer dye, and any
ink sheet can be used as the sheet. As a means for providing heat
energy in the thermal transfer, any of the conventionally known
providing means may be used. For example, application of a heat
energy of about 5 to 100 mJ/mm.sup.2 by controlling recording time
in a recording device such as a thermal printer (trade name: Video
Printer VY-100, manufactured by Hitachi, Ltd.), sufficiently
attains the expected result.
[0199] Also, the heat-sensitive transfer image-receiving sheet of
the present invention may be used in various applications enabling
thermal transfer recording, such as heat-sensitive transfer
image-receiving sheets in a form of thin sheets (cut sheets) or
rolls; cards; and transmittable type manuscript-making sheets, by
optionally selecting the type of support.
[0200] The present invention can be applied to a printer, a copying
machine and the like, each of which uses a heat-sensitive transfer
recording system.
[0201] The present invention provides a heat-sensitive transfer
image-receiving sheet which produces high-quality images of high
densities and reduced image defects at low costs, a manufacturing
method thereof, and an image-forming method using the same.
[0202] The heat-sensitive transfer image-receiving sheet of the
present invention can give high-quality images of high densities
and reduced image defects, and it can be manufactured with low
production costs.
[0203] The present invention will be described in more detail based
on the following examples, but the invention is not intended to be
limited thereto.
EXAMPLES
[0204] In the following Examples, the terms "part" and "%" are
values by mass, unless they are indicated differently in
particular.
(Preparation of Ink Sheet)
[0205] A polyester film 6.0 .mu.m in thickness (trade name:
Lumirror, manufactured by Toray Industries, Inc.) was used as the
substrate film. A heat-resistant slip layer (thickness: 1 .mu.m)
was formed on the back side of the film, and the following yellow,
magenta, and cyan compositions were respectively applied as a
monochromatic layer (coating amount: 1 g/m.sup.2 after drying) on
the front side. TABLE-US-00001 Yellow composition Dye (trade name:
Macrolex Yellow 6G, 5.5 parts by mass manufactured by Byer)
Polyvinylbutyral resin (trade name: ESLEC BX-1, 4.5 parts by mass
manufactured by Sekisui Chemical Co., Ltd.) Methyl ethyl
ketone/toluene (1/1, at mass ratio) 90 parts by mass Magenta
composition Magenta dye (trade name; Disperse Red 60) 5.5 parts by
mass Polyvinylbutyral resin (trade name: ESLEC BX-1, 4.5 parts by
mass manufactured by Sekisui Chemical Co., Ltd.) Methyl ethyl
ketone/toluene (1/1, at mass ratio) 90 parts by mass Cyan
composition Cyan dye (Solvent Blue 63) 5.5 parts by mass
Polyvinylbutyral resin (trade name: ESLEC BX-1, 4.5 parts by mass
manufactured by Sekisui Chemical Co., Ltd.) Methyl ethyl
ketone/toluene (1/1, at mass ratio) 90 parts by mass
(Preparation of Image-Receiving Sheet) (Preparation of support)
[0206] A pulp slurry was prepared from 50 parts by mass of hardwood
bleach kraft pulp (LBKP) of acacia origin and 50 parts by mass of
hardwood bleach kraft pulp (LBKP) of aspen origin, by beating these
pulps by means of a disk refiner until Canadian standard freeness
reached to 300 ml.
[0207] To the pulp slurry thus prepared were added, on a pulp
basis, 1.3 mass % of modified cationic starch (CAT0304L, trade
name, manufactured by Nippon NSC), 0.15 mass % of anionic
polyacrylamide (DA4104, trade name, manufactured by Seiko PMC
Corporation), 0.29 mass % of an alkylketene dimer (SIZEPINE K,
trade name, manufactured by Arakawa Chemical Industries, Ltd.),
0.29 mass % of epoxidated behenic acid amide, and 0.32 mass % of
polyamide polyamine epichlorohydrin (ARAFIX 100, trade name,
manufactured by Arakawa Chemical Industries, Ltd.), and thereafter
0.12 mass % of a defoaming agent was further added.
[0208] The resulting pulp slurry was made into paper by use of a
fourdrinier paper machine. In a process of drying in which the felt
side of web was pressed against a drum dryer cylinder via a dryer
canvas, the web thus formed was dried under a condition that the
tensile strength of the dryer canvas was adjusted to 1.6 kg/cm.
Then, each side of the raw paper thus made was coated with 1
g/m.sup.2 of polyvinyl alcohol (KL-118, trade name, manufactured by
Kuraray Co., Ltd.) with a size press, then, dried and further
subjected to calendering treatment. Therein, the papermaking was
performed so that the raw paper had a grammage (basis weight) of
157 g/m.sup.2, and the raw paper (base paper) having a thickness of
160 .mu.m was obtained.
[0209] The wire side (back side) of the base paper obtained was
subjected to corona discharge treatment, and thereto a resin
composition, in which a high-density polyethylene having an MFR
(which stands for a melt flow rate, and hereinafter has the same
meaning) of 16.0 g/10 min and a density of 0.96 g/cm.sup.3
(containing 250 ppm of hydrotalcite (DHT-4A (trade name),
manufactured by Kyowa Chemical Industry Co., Ltd.) and 200 ppm of a
secondary antioxidant (tris(2,4-di-t-butylphenyl)phosphite,
Irugaphos 168 (trade name), manufactured by Ciba Specialty
Chemicals)) and a low-density polyethylene having an MFR of 4.0
g/10 min and a density of 0.93 g/cm.sup.3 were mixed at a ratio of
75 to 25 by mass, was applied so as to have a thickness of 21
g/m.sup.2, by means of a melt extruder, thereby forming a
thermoplastic resin layer with a mat surface. (The side to which
this thermoplastic resin layer was provided is hereinafter referred
to as "back side"). The thermoplastic resin layer at the back side
was further subjected to corona discharge treatment, and then
coated with a dispersion prepared by dispersing into water a 1:2
mixture (by mass) of aluminum oxide (ALUMINASOL 100, trade name,
manufactured by Nissan Chemical Industries, Ltd.) and silicon
dioxide (SNOWTEX O, trade name, manufactured by Nissan Chemical
Industries, Ltd.), as an antistatic agent, so that the coating had
a dry mass of 0.2 g/m.sup.2. Subsequently, the front surface (front
side) of the base paper was subjected to corona discharge
treatment, and then coated with 27 g/m.sup.2 of a low-density
polyethylene having an MFR of 4.0 g/10 min and a density of 0.93
g/m.sup.3 and containing 10 mass % of titanium oxide, by means of a
melt extruder, thereby forming a thermoplastic resin layer with a
specular surface.
(Preparation of Emulsified Dispersion)
[0210] An emulsified dispersion A was prepared in the following
manner. An antioxidizing agent (EB-9) was dissolved in a mixture of
42 g of a high-boiling solvent (Solv-5) and 20 ml of ethyl acetate,
and the resulting solution was emulsified and dispersed in 250 g of
a 20 mass % aqueous gelatin solution containing 1 g of sodium
dodecylbenzenesulfonate by means of a high-speed stirring
emulsification machine (dissolver). Thereto, water was added to
prepare 380 g of an emulsified dispersion A.
[0211] Therein, the addition amount of the antioxidizing agent
(EB-9) was adjusted so that the antioxidizing agent would be
contained in an amount of 30 mol % in the emulsified dispersion
A.
(Preparation of Hollow Polymer Particles)
[0212] Nippol MH-5055 (solid: 30%, manufactured by Zeon
Corporation) was filtered through Epocel MCY 1001EE-13H (rated
filtration accuracy: 10 .mu.m, manufactured by Nihon Pall Ltd.)
four times. The dispersion after the treatment was called hollow
polymer particles (1).
[0213] Analysis of the 50-time diluted solution of the hollow
polymer particles (1) with FPIA-21,000 (manufactured by Sysmex
Corp.) showed that there were four bulky particles of 10 .mu.m or
more in a total of 12,356 particles. Thus, the ratio of the bulky
particles of 10 .mu.m or more in the total particles, (the number
of bulky particles)/(the number of all particles), was 1/6178.
[0214] Similarly, MH-5055 was filtered through MCY-1001EG (rated
filtration accuracy; 30 .mu.m, manufactured by Nihon Pall Ltd.)
once, to give a hollow polymer particles (2).
[0215] The ratio of the bulky particles of 10 .mu.m or more in the
total particles of the hollow polymer particles (2), (the number of
bulky particles)/(the number of all particles), was 1/3048.
[0216] The ratio of the bulky particles of 10 .mu.m or more
contained with respect to the total particles in the MH-5055
without filtration treatment, (the number of bulky particles)/(the
number of all particles), was 1/1232.
(Preparation of Hollow Polymer Particles (3) and (4))
[0217] Six parts of a monomer mixture (a) consisting of 50% ethyl
acrylate (EA), 5% butyl acrylate (BA) and 45% methacrylic acid
(MAA), 0.03 part of sodium dodecylbenzenesulfonate (DBSN), and 48
parts of ion-exchanged water were mixed and stirred to give an
emulsion (A); separately, 25 parts of a monomer mixture (b)
consisting of 78% MMA and 22% BA for forming the intermediate
layer, 0.075 part of DBSN and 35 parts of ion-exchanged water were
mixed and stirred to give an emulsion (B); and 75 parts of styrene,
0.075 part of DBSN, and 33 parts of ion-exchanged water were mixed
to give an emulsion (C).
[0218] Then, 17 parts of ion-exchanged water and 0.5 parts by
weight of an acrylic seed latex solution having a particle diameter
of 35 nm and a solid matter concentration of 12% were placed in a
reactor equipped with a stirrer, a reflux condenser tube, a
thermometer, and a separatory funnel, and the mixture was heated to
80.degree. C.
[0219] Then, 1 part of 3% potassium persulfate (KPS) solution was
added from the separatory funnel; the emulsion (A) was added over a
period of 4 hours; and the mixture was additionally kept at
80.degree. C. for 1 hour. Subsequently, 256 parts of ion-exchanged
water and 3.5 parts of 3% aqueous KPS solution were added, and the
emulsion (B) was added over 2 hours.
[0220] After the completion of the addition, the mixture was heated
to 85.degree. C.; 3.5 parts of 3% aqueous KPS solution was added,
and then, a half of the emulsion (C) was added over 1.5 hours.
After the addition, the mixture was allowed to react at 85.degree.
C. for 1 hour.
[0221] Subsequently, 10 parts of 10% sodium hydroxide solution was
added from the separatory funnel; the mixture was kept at
85.degree. C. for 30 minutes and treated with a base; 33 parts of
3% aqueous KPS solution was added thereto; and the other half of
the emulsion (C) was added over 1.5 hours. The mixture was then
allowed to stand for polymerization reaction additionally for 2
hours and then concentrated in an evaporator so as to have a solid
matter content of 30%, to give hollow polymer particles (3).
[0222] The thus-obtained hollow polymer particles had an average
particle diameter of 510 nm and a hollow ratio of 31%. The content
of particles with a size of 90% or less of the average particle
diameter (smaller particle ratio) was 25%, while that of the
particles with a size of 110% or more of the average particle
diameter (larger particle ratio) was 12%.
[0223] The ratio of the bulky particles of 10 .mu.m or more in all
particles of the hollow polymer thus obtained without filtration,
(the number of bulky particles)/(the number of all particles), was
1/3832. The hollow polymer particles were filtered through Epocel
MCY-1001 EE once, to give a hollow polymer particles (4).
[0224] The ratio of the bulky particles of 10 .mu.m or more in the
total particles of the hollow polymer particles (4), (the number of
bulky particles)/(the number of all particles), was 1/5120.
(Preparation of Image-Receiving Sheet)
[0225] An image-receiving sheet (1) was prepared on the support
prepared in the foregoing manner so as to form a multiple-layer
structure having a subbing (undercoat) layer 1, a subbing layer 2,
a heat insulation layer, and a receptor layer, in increasing order
of distance from the support. Compositions and application amounts
of the coating solutions used herein are shown below.
[0226] Coating was carried out according to the slide coating
method described in "LIQUID FILM COATING" p. 427, and the solutions
after coating were conveyed through a set zone at 6.degree. C. for
30 seconds to lose the solution fluidity, and then, the sheet was
dried by spraying drying air at 22.degree. C. and 45% RH on the
coated surface for 2 minutes. TABLE-US-00002 Coating solution for
subbing layer 1 (Composition) Aqueous solution prepared by adding
1% sodium dodecylbenzenesulfonate to 3% aqueous gelatin solution
NaOH for adjusting pH to 8 11 ml/m.sup.2 (Coating amount) Coating
solution for subbing layer 2 (Composition) Styrene-butadiene latex
(SR103 60 parts by mass (trade name), manufactured by Nippon A
& L Inc.) 6% Aqueous solution of polyvinyl 40 parts by mass
alcohol (PVA) NaOH for adjusting pH to 8 11 ml/m.sup.2 (Coating
amount) Coating solution for heat insulation layer (Composition)
Hollow polymer particles (1) 60 parts by mass 10% Gelatin aqueous
solution 60 parts by mass NaOH for adjusting pH to 8 Water 285
parts by mass (Coating amount) 50 ml/m.sup.2 Coating solution for
receptor layer (Composition) Vinyl chloride-series latex polymer 50
parts by mass (VINYBLAN 900, trade name, produced by Nissin
Chemical Industry Co., Ltd.) Vinyl chloride-series latex polymer 20
parts by mass (VINYBLAN 276, trade name, produced by Nissin
Chemical Industry Co., Ltd.) 10% Gelatin aqueous solution 10 parts
by mass Emulsified dispersion A prepared 10 parts by mass in the
above Microcrystalline wax (EMUSTAR-42X 5 parts by mass (trade
name), manufactured by Nippon Seiro Co., Ltd.) Water 5 parts by
mass NaOH for adjusting pH to 8 18 ml/m.sup.2 (Coating amount)
[0227] An image-receiving sheet (1-2) was prepared in the same
manner as the image-receiving sheet (1), except that the 10%
gelatin solution added to the heat insulation layer was replaced
with an equivalent amount of a mixed solution of 8% and 2% gelatin
solutions.
[0228] In addition, an image-receiving sheet (2) was prepared in
the same manner as the image-receiving sheet (1), except that the
hollow polymer particles (I) added to the heat insulation layer of
the image-receiving sheet (1) were replaced with the hollow polymer
particles (2). An image-receiving sheet (4) was prepared in the
same manner as the image-receiving sheet (1), except that the
hollow polymer particles (1) were replaced with the hollow polymer
particles (4). An image-receiving sheet (5) was prepared in the
same manner as the image-receiving sheet (1), except that the
hollow polymer particles (1) were replaced with MH-5055 particles
without filtration treatment.
[0229] An image-receiving sheet (1-3) was prepared in the same
manner as the image-receiving sheet (1), except that the heat
insulation layer of the image-receiving sheet (1) was replaced with
a layer formed with an undercoat coating solution (coating amount:
50 ml/m.sup.2).
(Image Formation)
[0230] A solid image of a signal (R, G, B) of (0, 0, 0) was formed
by using the ink sheet and the image-receiving sheet prepared above
from a thermal transfer printer ASK-2000 (manufactured by Fuji
Photo Film Co.), and the reflection density from the image was
measured. As representative value thereof, magenta density Dm, is
shown in Table 1. A gray solid image of D=1.0 in the KG size was
formed on 10 sheets for evaluation of image defects. The evaluation
results are tabulated in Table 1. TABLE-US-00003 TABLE 1
Image-receiving (1) (1-2) (4) (2) (5) (1-3) sheet Hollow polymer
(1) (1) (4) (2) MH-5055 Not used particles Number of bulky 1/6178
1/6178 1/5120 1/3048 1/1232 -- particles/Number of all particles Dm
2.18 2.22 2.23 2.18 2.17 1.98 Image defect, KG 3 defects 4 defects
3 defects 48 defects 72 defects 2 defects size, per 10 sheets
Remarks This This This Comparative Comparative Comparative
invention invention invention Example Example Example
[0231] The results in Table 1 show that there are significantly
lower image defects when the ratio of the bulky particles of 10
.mu.m or more in diameter in all particles is less than 1/5,000. In
addition, Dm is almost independent of the abundance ratio of bulky
particles, indicating that the heat-insulating efficiency is almost
independent of the ratio. The heat-insulating efficiency of the
heat insulation layer containing hollow polymer particles is higher
than that of the image-receiving sheet (1-3) containing no hollow
polymer particles.
[0232] The results indicate that it is possible to form an image at
higher density and obtain a high-quality image containing fewer
image defects by forming a heat insulation layer containing hollow
polymer particles having a ratio of the bulky particles of 10 .mu.m
or more in diameter in all particles at less than 1/5,000.
[0233] Having described our invention as related to the present
embodiments, it is our intention that the invention not be limited
by any of the details of the description, unless otherwise
specified, but rather be construed broadly within its spirit and
scope as set out in the accompanying claims.
* * * * *